ATENOLOL (Tenormin) Side Effects Guide

Table of Contents

Intro

Side Effects Overview Table

How Other Drugs Compare

Week-by-Week Timeline

Why Doctors Still Prescribe Tenormin

The Worst Side Effects

The Most Common Side Effects

Deep Dive: Drowsiness & Fatigue

Deep Dive: Shortness of Breath

Discontinuation & Withdrawal

Dosage by Condition

Alternatives

Clinical Trials

Decision Map

Monitoring & What to Track

Pregnancy & Breastfeeding

Emergency Warning Signs

Summary & Next Steps

Appendix A: FDA Label Data Summary

Appendix B: Reddit User-Reported Side Effects

Appendix C: Clinical Trials with Different Mechanisms

Appendix D: Methodology

Sources

Intro

Side Effects Overview Table

How Other Drugs Compare

Week-by-Week Timeline

Why Doctors Still Prescribe Tenormin

The Worst Side Effects

The Most Common Side Effects

Deep Dive: Drowsiness & Fatigue

Deep Dive: Shortness of Breath

Discontinuation & Withdrawal

Dosage by Condition

Alternatives

Clinical Trials

Decision Map

Monitoring & What to Track

Pregnancy & Breastfeeding

Emergency Warning Signs

Summary & Next Steps

Appendix A: FDA Label Data Summary

Appendix B: Reddit User-Reported Side Effects

Appendix C: Clinical Trials with Different Mechanisms

Appendix D: Methodology

Sources

Explore the real-world and clinical side effects of Tenormin (atenolol), a beta-blocker, with data from FDA trials and patient experiences. Understand what to expect, compare with alternatives, and see how emerging clinical trials may offer hope for fewer side effects.

Medication: Tenormin (ATENOLOL) Drug Class: beta-Adrenergic Blocker [EPC] Author: Michael Baskerville Gill, B. Sc.

Reviewed by the Power Medical Content Team

Intro

Day 1: You might feel a touch of lightheadedness and, if you're unlucky, a foggy sort of tired that’s hard to distinguish from general life fatigue. Day 3: For some, there's that unmistakable sensation that your blood pressure has taken a dive. Week 2: Either you’ve adjusted and mostly forgotten about Tenormin, or you’re deep in the Reddit forums comparing notes on brain fog.

Beta-blockers like Tenormin (generic: atenolol) are prescribed for everything from high blood pressure and post-heart attack care to off-label use for anxiety or POTS (postural orthostatic tachycardia syndrome). The draw? They reliably slow your heart and lower blood pressure by blocking beta-adrenergic receptors (proteins in your body that adrenaline binds to). But for every patient whose palpitations vanish, there’s someone else lamenting the drowsiness, the shortness of breath, or the insidious weight gain that creeps up months later.

The standard line is that most people tolerate beta-blockers well. But the word “most” doesn’t mean much if you’re the one trying to shake off brain fog at your desk. Side effect statistics can wildly mismatch real experience, and what’s rare on a checklist might be the one thing that derails your week.

→ Find clinical trials with new mechanisms and different side effects

Interested in clinical trials? Many trials for depression now target different mechanisms than beta-Adrenergic Blocker [EPC]—potentially offering different side effect profiles. Browse clinical trials →

Side Effects Overview Table

Side Effect	FDA Rate	Reddit Reports	Severity	Duration	Example
Feeling drowsy or run down	2% (Drowsiness)	🟡 occasional (3 posts)	🟢 mild	Up to 1 week, sometimes ongoing	source
Lethargy and increased fatigue	3% (Lethargy), 6% (Fatigue), 26% (Tiredness)	🟡 occasional (3 posts)	🟡 moderate	Ongoing if high dose, resolves with adjustment	source
Dizziness and feeling lightheaded	13% (Dizziness), 3% (Light-headedness)	🟡 occasional (3 posts)	🟡 moderate	First days to 2 weeks	source
Shortness of breath or difficulty taking a full breath	6% (Dyspnea)	🟡 occasional (3 posts)	🟡 moderate	Ongoing while on drug	source
Chest pain or angina	N/A	🟢 rare (2 posts)	🟡 moderate	While on drug, resolves after stopping	source
Brain fog or cognitive dulling	N/A	🟢 rare (2 posts)	🟢 mild	Ongoing while on drug	source
Weight gain and increased setpoint weight	N/A	🟢 rare (1 post)	🟠 severe	Months	source
Increased triglyceride levels	N/A	🟢 rare (1 post)	🟡 moderate	Months, resolves after stopping	source
Vertigo while adjusting dosage	2% (Vertigo)	🟢 rare (1 post)	🟢 mild	During dose adjustment	source
Neck and shoulder pain	N/A	🟢 rare (1 post)	🟡 moderate	Ongoing while on drug	source
Difficulty falling or staying asleep	N/A	🟢 rare (1 post)	🟡 moderate	Ongoing while on drug	source
Brain zaps while on atenolol	N/A	🟢 rare (1 post)	🟡 moderate	Ongoing while on drug	source
Withdrawal symptoms when reducing or missing a dose	N/A	🟢 rare (1 post)	🟡 moderate	During withdrawal or missed dose	source
Blood pressure lowered too much	N/A	🟢 rare (1 post)	🟡 moderate	While on drug	source

→ View all 70 side effects from FDA trials → View all 14 user-reported side effects

How Other Drugs Compare

If you're weighing options, here's how Tenormin stacks up against alternatives:

Metric	Tenormin (beta-Adrenergic Blocker [EPC])	CYB003 (Deuterated Psilocybin Analog)	Osavampator (AMPA-PAM)	D-cycloserine (NMDA Partial Agonist)
MECHANISM
Drug class	Beta-Adrenergic Blocker	5-HT2A Agonist (psychedelic-derived)	AMPA Positive Allosteric Modulator	NMDA Partial Agonist
How it works	Blocks adrenaline binding at beta-adrenergic receptors (slows heart rate, lowers BP)	Activates 5-HT2A receptor, rapidly alters mood/cognition	Enhances glutamate transmission (excitatory)	Modulates glutamate via NMDA receptor
EFFICACY
Response rate	N/A for depression; 60-80% BP control in hypertension	53.8% (3 wks MDD) source	Not yet reported	Not reported
Remission rate	N/A for depression; up to 75% in BP/angina studies	75% (4 months MDD) source	Not yet reported	Not reported
Time to effect	Hours for BP, days to weeks for symptoms	1-3 weeks	Expected days-weeks	1-2 weeks
KEY SIDE EFFECTS
Feeling drowsy/run down	2%	Rare (mild, transient)	Not reported	Not reported
Lethargy/fatigue	26% (Tiredness)	N/A	N/A	N/A
Dizziness	13%	Mild/transient	Mild/transient	Mild
Weight gain	N/A	None observed	None observed	None observed
Sexual dysfunction	Postmarketing, rare	None observed	None observed	None observed

→ Find clinical trials matched to your situation

Week-by-Week Timeline

Week	Common Experiences	What's Normal	When to Call Your Doctor
Week 1	Drowsiness, dizziness, fatigue	Startup effects	Severe bradycardia (slow HR), fainting
Week 2-3	Dizziness, tiredness may persist or start to fade	Adjustment period	Chest pain, new or severe shortness of breath
Week 4-6	Most benefits apparent (BP lower, palpitations improved)	Effects stabilize	Persistent severe fatigue, intolerable side effects
Week 6-8	Side effects often faded; stable response	Stable	No improvement or worsening symptoms

Most side effects peak in Week 1-2 and improve by Week 4.

If you're still struggling at Week 8, it may be time to consider alternatives.

→ Explore clinical trials with faster onset

Why Doctors Still Prescribe Tenormin

Tenormin works by blocking beta-adrenergic receptors—proteins on heart and blood vessel cells that adrenaline normally binds to. By denying adrenaline the keys to these locks, your heart rate and blood pressure drop. Simple in concept, if not in execution.

Most of its side effects, like drowsiness, fatigue, and dizziness, come from this broad reduction in your body’s stress response. It’s not just your heart that gets the memo; your brain, lungs, and metabolism are all caught in the crossfire.

So why do doctors stick with it? For all its baggage, Tenormin has been around for decades, with thousands of trial patients behind each dosing recommendation. It’s predictable—your doctor knows what to expect and (usually) how to fix it if things go sideways. Plus, for hypertension, post-heart attack, and certain kinds of anxiety, it’s tough to find an alternative that’s as simple, cheap, and reliable. The trade-off? You gain heart protection and symptom control, but you may lose some pep, breath, or even a few pounds you didn’t want to.

The Worst Side Effects

Let’s not sugarcoat this: a handful of Tenormin side effects show up as the stuff that derails people’s routines—sometimes even forcing a quit.

Weight gain and increased setpoint weight

"I've been on atenolol since October and my setpoint weight seems to have increased. It's greatly distressing to me and triggered an ED relapse." source

Reported as severe by 1/1 users mentioning this side effect
Management tip: Ask your doctor for baseline and regular follow-up weight checks. If you notice steady gain, alternative medications (like nebivolol or non-beta-blocker agents) may avoid this issue. For some, lifestyle interventions aren’t enough.

Lethargy and increased fatigue

"If you are taking more than 50mg a day it will make you so lethargic." source

Rated moderate by 2/3 users
Management tip: Lowering the dose often helps. Consider timing doses at night if cleared by your doctor, or switching to a beta-blocker with fewer CNS effects.

Dizziness and feeling lightheaded

"It can cause dizziness... especially in the first few days or 1-2 weeks on it" source

Rated moderate by all users
Management tip: Hydrate, rise slowly from sitting or lying, and check with your doctor if symptoms don’t ease by week two or if you faint.

Shortness of breath or difficulty taking a full breath

"I was constantly out of breath... dealing with brain zaps, and felt effects of a 'withdrawal dose'" source

Rated moderate by all users mentioning this (3/3)
Management tip: If you have a history of asthma or other lung disease, Tenormin is often contraindicated—let your provider know immediately.

How Clinical Trials Compare

CYB003 (psilocybin analog) Phase 2 showed no weight gain, sedation, or sexual dysfunction vs. weight gain and sedation for Tenormin. Mild headache and transient nausea were the most frequent complaints in trial participants source.

→ Find trials with lower rates of these side effects

The Most Common Side Effects

Feeling drowsy or run down

FDA: 2%, Reddit: 3 posts (all mild)
"Brain fog and drowsiness are a few [side effects]" source
What helps: Take at night, split dose, expect some adjustment in first week. Most find it fades after 1-2 weeks.

Lethargy and increased fatigue

FDA: 26% (Tiredness), 6% (Fatigue), Reddit: 3 posts (moderate)
"If you are taking more than 50mg a day it will make you so lethargic." source
What helps: Dose reduction, take with food or at bedtime. Often dose-dependent, so check if you’re at the higher end.

Dizziness and feeling lightheaded

FDA: 13% (Dizziness), Reddit: 3 posts (moderate)
"It can cause dizziness... especially in the first few days or 1-2 weeks on it." source
What helps: Rise slowly, hydrate, and consider a morning dose. Usually fades within a week or two.

Shortness of breath or difficulty taking a full breath

FDA: 6% (Dyspnea), Reddit: 3 posts (moderate)
"Since starting Atenolol at 12.5 mg, I've experienced angina and dyspnea. Symptoms I've never experienced at this level." source
What helps: Evaluate for preexisting asthma, ask about switching to a more cardioselective beta-blocker.

Brain fog or cognitive dulling

FDA: Not reported, Reddit: 2 posts (mild)
"Brain fog and drowsiness are a few [side effects]." source
What helps: Monitor after first week; if it persists or worsens, talk to your doctor.

Management tip: Most of these effects resolve within 1-2 weeks, but persistent, severe, or intolerable symptoms should prompt a medication review.

Deep Dive: Drowsiness & Fatigue

"Brain fog and drowsiness are a few [side effects]." source

Drowsiness is not just a warning on the label—it’s a daily frustration for a subset of Tenormin users. On the FDA label, drowsiness shows up in about 2% of clinical trial participants, but if you scan patient discussions, it pops up more often (3 posts here, all rated as mild). It’s one of those annoyances that blurs into the background fatigue from disrupted sleep or a slower resting heart rate.

Most users find that drowsiness emerges within the first few days. Some feel "really run down" source, others just need an extra nap. The mechanism? By blocking beta-adrenergic receptors (preventing adrenaline’s effects), Tenormin not only cools off your cardiovascular system—it also blunts the natural upticks in energy you’d get during the day.

Management tips: Try taking your dose at night, with food, or discuss dose splitting with your provider. For most, this symptom fades by week two. If you’re nodding off at meetings past that point, it may be worth exploring an alternative or adjusting the dose.

Deep Dive: Shortness of Breath

Shortness of breath—technically, dyspnea (difficulty getting enough air)—is the sort of side effect you don’t really appreciate until you find yourself breathing shallowly at your desk.

"I'm in an endless cycle of fight or flight, neck + shoulder pain, feeling like I can't take a full breath, not sleeping even when I try." source

On the FDA label, dyspnea is reported in 6% of users, but in patient communities it's a repeated concern (3 posts, all moderate severity). Mechanistically, this is expected: Tenormin blocks beta-receptors not just in the heart, but sometimes in the lungs—especially in people with pre-existing asthma or respiratory problems. That’s why patients with asthma are usually steered toward cardioselective alternatives.

Management tips: If you’re feeling out of breath (especially if you have any personal or family history of asthma or COPD), let your provider know immediately. This is one of the beta-blocker side effects that isn’t just annoying—it can be dangerous. For many, switching drugs or dose adjustment can resolve it entirely.

Discontinuation & Withdrawal

How common are withdrawal effects? With Tenormin and other beta-blockers, sudden discontinuation can result in rebound hypertension (your blood pressure skyrockets back, sometimes even higher), chest pain, palpitations, and in rare cases, heart attacks—especially if you have coronary disease.

Beta-blockers’ half-life (how long they stay active in your body) makes a difference. Atenolol’s half-life is about 6-9 hours, so abrupt cessation clears your system in less than two days. That fast drop-off can mean withdrawal symptoms come on quickly—sometimes within hours to a day or two. One user describes, "I was constantly out of breath, dealing with brain zaps, and felt effects of a 'withdrawal dose'" after missing or reducing their dose source.

Management tips: Always taper under a doctor’s supervision. For most, a reduction by 25% every week (sometimes every 2 weeks for those sensitive to withdrawal) is safe. Monitor for palpitations, blood pressure spikes, chest pain, or anxiety. If any emerge, pause the taper and consult your provider.

Timeline: Withdrawal symptoms typically last several days to a week, but may be more severe or prolonged in those with underlying cardiovascular disease.

Dosage by Condition

Condition	Starting Dose	Typical Dose	Maximum Dose
Hypertension	25-50 mg once daily	50-100 mg once daily	100 mg once daily
Angina Pectoris	50 mg once daily	50-100 mg once daily	200 mg daily (single or divided dose)
Acute Myocardial Infarction	50 mg twice daily after initial IV dose	100 mg once daily	100 mg once daily

Dose-response: Higher doses may increase fatigue, dizziness, and risk of bradycardia (abnormally slow heart rate). Start low, go slow—especially for older adults or those with kidney impairment.

Find Top Clinical Trials

Choose from over 30,000 active clinical trials.

Alternatives

Not everyone is destined to get along with Tenormin. Here's a quick personality match:

Bisoprolol or nebivolol (beta-1 selective blockers): More cardioselective—less likely to cause fatigue or breathing issues.
ACE inhibitors (e.g., lisinopril): No sedation or weight gain, but may cough.
Calcium channel blockers (e.g., amlodipine): More gentle for fatigue-prone, won’t slow pulse as much.
ARBs (e.g., losartan): Well-tolerated for blood pressure; rarely cause sedation or sexual side effects.

If Tenormin's particular side effects are haunting you (fatigue, shortness of breath, weight changes), these options may avoid the specific issues. Or, for those with depression, consider emerging options like CYB003 (psilocybin analog)—with rapid action and without chronic drowsiness or weight gain.

→ Compare your options on WithPower

Clinical Trials

If you're at your wit’s end with beta-blocker fatigue or weight gain, there are alternatives being studied:

CYB003 (deuterated psilocybin analog, NCT06141876): Works via 5-HT2A receptor agonism; rapid and sustained antidepressant effect with no weight gain, sedation, or sexual dysfunction. 53.8% response, 75% remission at 4 months source.
Osavampator (AMPA-PAM): Acts on glutamate system, not associated with sedation or weight gain, phase 3 underway source.
D-cycloserine (NMDA partial agonist, NCT00408031): Mild side effects, acts rapidly as adjunct in TRD. Not associated with weight gain, sedation, or withdrawal.
Classic psilocybin (various): No sexual dysfunction, weight gain, or ongoing sedation. Acute effects (e.g., anxiety, headache) resolve quickly.

Trial participation means careful screening, some risk of placebo, but access to new mechanisms and rigorous safety monitoring. Most are conducted free of charge, often with medical oversight not found in standard care. Phase 2 and 3 trials are not a guarantee of efficacy or safety—they're how we find out what really works.

Interested in clinical trials? Many trials for depression now target different mechanisms than beta-Adrenergic Blocker [EPC]—potentially offering different side effect profiles. Browse clinical trials →

Decision Map

If lethargy/fatigue is the dealbreaker → bisoprolol (cardioselective beta-blocker), ACE inhibitors, or CYB003 trial (psilocybin analog)

If weight gain is the dealbreaker → nebivolol, ARBs, or Osavampator/AMPA-PAM trials

If shortness of breath is the dealbreaker → switch to a cardioselective beta-blocker (bisoprolol, metoprolol) or a non-beta-blocker option.

If dizziness/lightheadedness is the dealbreaker → dose titration, split dosing, consider calcium channel blocker.

Always discuss risks and tradeoffs with your doctor—and you can always see trials tailored to your profile.

Tenormin (Atenolol) - antidepressant medication Image: Plushcare.com

Monitoring & What to Track

Your doctor should monitor:

Blood pressure (standing and seated)
Pulse (HR)
Electrocardiogram (if at risk of heart block)
Weight (for insidious gain)
Renal function (BUN/Creatinine in those at risk)
For anxiety/POTS: Symptom diary, episodes per week

You should track:

Energy/fatigue (1-10 daily)
Lightheadedness/dizziness (noting timing and dose relation)
Breathlessness episodes (with activity and at rest)
Mood/mental clarity (“brain fog” log)
Sleep quality and exercise tolerance

If your doctor isn't tracking these, ask them to. Sometimes, patients spot patterns clinicians miss.

Pregnancy & Breastfeeding

Tenormin is Pregnancy Category D (positive evidence of risk). Use in pregnancy is generally not recommended unless the benefit outweighs the risk. Atenolol can cause fetal harm—especially growth restriction—when given during the second or third trimester FDA label.

Risks:

Fetal growth restriction
Neonatal bradycardia (slow heart rate)
Hypoglycemia

Breastfeeding: Atenolol is excreted in breast milk. There is a risk of bradycardia and hypoglycemia in the nursing infant—especially with premature babies or those with renal issues.

Key message: This is always a risk-benefit discussion with your doctor—not a simple yes/no. For some mothers, untreated hypertension poses even greater risk. Never stop abruptly if you become pregnant; your doctor will guide a careful taper or switch.

Emergency Warning Signs

⚠️ Call 911 or go to ER immediately if you experience:

Severe chest pain or tightness
Difficulty breathing or wheezing not typical for you
Signs of shock: clammy skin, confusion, rapid weak pulse
Sudden severe dizziness or loss of consciousness

📞 Call your doctor urgently if:

New or worsening swelling in the legs, feet, or abdomen
Severe fatigue not improved with rest
Unusual bruising, rash, or signs of allergic reaction (swelling of face, lips, tongue, or throat)
New or worsening depression, confusion, or psychosis
Persistent slow heartbeat (especially under 50 beats/min)

Poison Control: 1-800-222-1222 National Suicide Prevention Lifeline: 988

Summary & Next Steps

Key takeaways: Tenormin (atenolol) is well-studied, but 26% of users in trials report tiredness, and up to 13% experience dizziness—with real-world patients often citing lethargy, shortness of breath, or weight gain as dealbreakers. Most startup side effects resolve by week 2-4, but if you’re among those with persistent or intolerable symptoms, alternatives exist.

If Tenormin is working for you:

Keep monitoring your symptoms and side effects; track your energy and mood.
Don’t change your dose suddenly without medical advice.

If side effects are intolerable:

Bring this guide (and your symptom log) to your doctor.
Ask about dose adjustment or alternative drugs like bisoprolol, nebivolol, or ARBs.
Consider clinical trials of new drug classes (like CYB003) that sidestep weight gain and sedation.

Your next steps:

Track your symptoms for 2 weeks using a mood/energy diary
Discuss this side effect guide with your doctor
If considering alternatives, → explore clinical trials

→ Find clinical trials matched to your situation

Appendix A: FDA Label Data Summary

Adverse Reactions by Prevalence (Clinical Trial Data)

Side Effect	Drug Rate	Placebo Rate	Category	System
Tiredness	26%	13%	very common	Nervous System
Hypotension (acute MI) ⚠️	25%	15%	very common	Cardiovascular
Heart failure (acute MI) ⚠️	19%	24%	very common	Cardiovascular
Bradycardia (acute MI) ⚠️	18%	10%	very common	Cardiovascular
Ventricular tachycardia (acute MI) ⚠️	16%	22%	very common	Cardiovascular
Hypotension/bradycardia (ISIS-1) ⚠️	14.5%	0%	common	Cardiovascular
Dizziness	13%	6%	very common	Nervous System
Cold extremities	12%	5%	common	Cardiovascular
Depression	12%	9%	common	Psychiatric
Supraventricular tachycardia (acute MI) ⚠️	11.5%	19%	common	Cardiovascular
Fatigue	6%	5%	common	Nervous System
Dyspnea	6%	4%	common	Respiratory
Atrial fibrillation (acute MI) ⚠️	5%	11%	common	Cardiovascular
Heart block (acute MI) ⚠️	4.5%	4.3%	common	Cardiovascular
Postural hypotension	4%	5%	common	Cardiovascular
Bradycardia	3%	0%	common	Cardiovascular
Leg pain	3%	1%	common	Musculoskeletal
Light-headedness	3%	0.7%	common	Nervous System
Lethargy	3%	0.7%	common	Nervous System
Dreaming (vivid dreams)	3%	1%	common	Psychiatric
Diarrhea	3%	2%	common	Gastrointestinal
Nausea	3%	1%	common	Gastrointestinal
Wheeziness	3%	3%	common	Respiratory
Deaths (acute MI) ⚠️	2.9%	6.9%	rare	Cardiovascular
Cardiac failure (ISIS-1) ⚠️	2.9%	0%	rare	Cardiovascular
Vertigo	2%	0.2%	common	Nervous System
Drowsiness	2%	0.5%	common	Nervous System
Heart block > first degree (ISIS-1) ⚠️	1.7%	0%	rare	Cardiovascular
Atrial flutter (acute MI) ⚠️	1.6%	3%	uncommon	Cardiovascular
Total cardiac arrests (acute MI) ⚠️	1.6%	6.9%	uncommon	Cardiovascular

Drug Interactions

Catecholamine-depleting drugs (e.g., reserpine): additive effect, risk of hypotension/bradycardia/vertigo/syncope/postural hypotension.
Calcium channel blockers: additive effect, risk of bradycardia or heart failure.
Disopyramide: risk of severe bradycardia, asystole, heart failure when combined with beta-blockers.
Amiodarone: additive negative chronotropic effects with beta-blockers.
Clonidine: risk of rebound hypertension if withdrawn with beta-blocker present; beta-blocker should be withdrawn first.
Prostaglandin synthase inhibitors (e.g., indomethacin): may decrease hypotensive effects of beta-blockers.
Digitalis glycosides: increased risk of bradycardia when combined with beta-blockers.
Aspirin: no clinical interaction observed in acute MI setting, but data limited.
Epinephrine: patients with history of anaphylaxis may be unresponsive to usual doses while on beta-blockers.

Appendix B: Reddit User-Reported Side Effects

Data extracted from Reddit discussions. Counts show how many posts/comments mentioned each side effect.

Side Effect	Mentions	Severity	Duration	Persists?
Feeling drowsy or run down	3 posts	🟢 Mild (3/3)	Ongoing for some, resolves after a week for others	Resolves
Lethargy and increased fatigue	3 posts	🟡 Moderate (2/3)	Ongoing if dose is high, otherwise may resolve after adjustment	Resolves
Dizziness and feeling lightheaded	3 posts	🟡 Moderate (3/3)	First few days to weeks, may resolve with time or dose adjustment	Resolves
Shortness of breath or difficulty taking a full breath	3 posts	🟡 Moderate (3/3)	Ongoing while on medication	Resolves
Chest pain or angina	2 posts	🟡 Moderate (2/2)	While on medication, resolves after stopping	Resolves
Brain fog or cognitive dulling	2 posts	🟢 Mild (2/2)	Ongoing while on medication	Resolves
Weight gain and increased setpoint weight	1 posts	🟠 Severe (1/1)	Ongoing while on medication	Resolves
Increased triglyceride levels	1 posts	🟡 Moderate (1/1)	Ongoing while on medication, resolved after stopping	Resolves
Vertigo while adjusting dosage	1 posts	🟢 Mild (1/1)	During dose adjustment period	Resolves
Neck and shoulder pain	1 posts	🟡 Moderate (1/1)	Ongoing while on medication	Resolves
Difficulty falling or staying asleep	1 posts	🟡 Moderate (1/1)	Ongoing while on medication	Resolves
Brain zaps while on atenolol	1 posts	🟡 Moderate (1/1)	Ongoing while on medication	Resolves
Withdrawal symptoms when reducing or missing a dose	1 posts	🟡 Moderate (1/1)	During dose reduction or missed dose	Resolves
Blood pressure lowered too much	1 posts	🟡 Moderate (1/1)	While on medication, resolves after stopping or dose adjustment	Resolves

User Quotes by Side Effect

Feeling drowsy or run down (Starts soon after beginning medication, may resolve after about a week)

"Brain fog and drowsiness are a few [side effects]." source

"The drowsiness could be your medication still affecting your blood pressure, keeping it low, and giving you that really run down feeling that..." source

"I did have some negative side effects when I first started taking it. They subsided if I remember correctly after about a week..." source

Lethargy and increased fatigue (Starts after beginning medication or dose increase, may persist if dose remains high)

"If you are taking more than 50mg a day it will make you so lethargic." source

"It made me more tired. But it didn't give me PEM or worsen ME/CFS in a way..." source

"I am on Atenolol 25mg for high blood pressure and anxiety and today just felt totally out of breath and miserable after doing 1km in 5 minutes." source

Dizziness and feeling lightheaded (Starts within first days, peaks in first week, often resolves after 1-2 weeks or with dose adjustment)

"Starting a beta blocker you will generally have more side effects than you will after a few days or 1-2 weeks on it -- in my experience it can cause dizziness..." source

"I took Atenolol and now seem too calm and about to faint, I'm new to anxiety medications so I would like to know what's it like to take it." source

"At first while we were fine tuning the dosage, I had some side effects like dizzy spells and occasional vertigo." source

Shortness of breath or difficulty taking a full breath (Starts soon after beginning medication, persists while on it)

"I'm in an endless cycle of fight or flight, neck + shoulder pain, feeling like I cant take a full breath, not sleeping even when I try." source

"Since starting Atenolol at 12.5 mg, ive experienced angina and dyspnea. Symptoms i've never experienced at this level." source

"I just felt weird all the time on it - I was constantly out of breath, dealing with brain zaps, and felt effects of a “withdrawal dose” (aka..." source

Chest pain or angina (Starts after beginning medication, resolves after stopping)

"Since starting Atenolol at 12.5 mg, ive experienced angina and dyspnea. Symptoms i've never experienced at this level." source

"Also, atenolol gave me the worst daily chest pains that completely went away once I stopped it." source

Brain fog or cognitive dulling (Starts after beginning medication, persists while on it)

"Brain fog and drowsiness are a few [side effects]." source

"Just started propranolol a week ago, but noticing it's affecting me with dizziness, brain fog, depression, break-through anxiety in between doses." source

Weight gain and increased setpoint weight (Develops over months of use)

"I've been on atenolol since October and my setpoint weight seems to have increased. It's greatly distressing to me and triggered an ED relapse." source

Increased triglyceride levels (Develops over months, resolves after stopping)

"Not 100% confirmed but believe it tripled my triglycerides. Stopped taking it and..." source

Vertigo while adjusting dosage (Occurs during initial dose adjustment, resolves after stabilization)

"At first while we were fine tuning the dosage, I had some side effects like dizzy spells and occasional vertigo." source

Neck and shoulder pain (Starts after beginning medication, persists while on it)

"I'm in an endless cycle of fight or flight, neck + shoulder pain, feeling like I cant take a full breath, not sleeping even when I try." source

Difficulty falling or staying asleep (Starts after beginning medication, persists while on it)

"I'm in an endless cycle of fight or flight, neck + shoulder pain, feeling like I cant take a full breath, not sleeping even when I try." source

Brain zaps while on atenolol (Starts after beginning medication, persists while on it)

"I was constantly out of breath, dealing with brain zaps, and felt effects of a “withdrawal dose” (aka..." source

Withdrawal symptoms when reducing or missing a dose (Occurs during dose reduction or missed dose, resolves after stabilization or resuming)

"I was constantly out of breath, dealing with brain zaps, and felt effects of a “withdrawal dose” (aka..." source

Blood pressure lowered too much (Starts after beginning medication, resolves after stopping or dose adjustment)

"Atenolol lowered my blood pressure too much so it wasn't a good fit. It made me more tired." source

Appendix C: Clinical Trials with Different Mechanisms

These trials target mechanisms different from beta-Adrenergic Blocker [EPC]. Phase 2 results do not guarantee Phase 3 success.

CYB003 (deuterated psilocybin analog)

Sponsor: Cybin Inc.
Phase: Phase 2 (Breakthrough Therapy Designation)
NCT: NCT06141876
Mechanism: Deuterated psilocybin analog (psychedelic-derived, 5-HT2A receptor agonist)
Side Effect Comparison: CYB003 showed a favorable side effect profile: transient mild-moderate headache and nausea were most common, with no evidence of sexual dysfunction, weight gain, or cognitive impairment typical of SSRIs/SNRIs. No serious adverse events reported.
Efficacy Data:
- Response rate: 53.8% (CYB003 16mg) vs 19.2% (placebo) at 3 weeks
- Remission rate: 75% at 4 months (CYB003)
- MADRS change: -14.08 points (CYB003 16mg) vs -8.24 points (placebo) at 3 weeks
- Time to response: 1-3 weeks
- Source
Why it might interest you: CYB003 acts via a novel psychedelic mechanism, offering rapid and sustained antidepressant effects with a single or few doses. It avoids common SSRI/SNRI side effects (sexual dysfunction, weight gain, emotional blunting), and has a much faster onset of action.
Results: Significant and rapid reduction in depressive symptoms; high remission rates sustained at 4 months; well-tolerated in trial population.
Sources: 1, 2, 3

Osavampator (NBI-1065845, TAK-653)

Sponsor: Neurocrine Biosciences
Phase: Phase 3
Mechanism: AMPA receptor positive allosteric modulator (AMPA-PAM)
Side Effect Comparison: AMPA modulators like osavampator are not associated with sexual dysfunction, weight gain, or sedation typical of SSRIs/SNRIs. Early data suggest a favorable side effect profile, with low rates of cognitive or metabolic adverse effects.
Efficacy Data:
- Response rate: Not yet reported (Phase 3 ongoing)
- Remission rate: Not yet reported (Phase 3 ongoing)
- MADRS change: Not yet reported (Phase 3 ongoing); Phase 2 showed significant improvement over placebo
- Time to response: Expected to be faster than SSRIs (based on AMPA mechanism)
- Source
Why it might interest you: Osavampator targets glutamatergic neurotransmission (AMPA), a completely different pathway from standard antidepressants. It may offer faster onset and fewer side effects (especially less sexual dysfunction, weight gain, or sedation) than SSRIs/SNRIs.
Results: Phase 2 data showed significant improvement in depressive symptoms as adjunctive therapy; Phase 3 is ongoing to confirm efficacy and safety.
Sources: 1, 2, 3

D-cycloserine (adjunctive)

Sponsor: Not specified (academic/NIH)
Phase: Phase 2 (completed)
NCT: NCT00408031
Mechanism: NMDA receptor partial agonist (glycine site modulator)
Side Effect Comparison: D-cycloserine is not associated with sexual dysfunction, weight gain, or sedation. Side effects are generally mild (headache, dizziness) and less frequent than with SSRIs/SNRIs.
Efficacy Data:
- Response rate: Not reported
- Remission rate: Not reported
- MADRS change: Not specified for D-cycloserine in MDD; in TRD, significant improvement over placebo in phase 2 trial (NCT00408031)
- Time to response: Within 2 weeks (in adjunctive use)
- Source
Why it might interest you: D-cycloserine works via NMDA modulation, offering a novel mechanism with rapid onset and a side effect profile that avoids the most common issues with standard antidepressants.
Results: Adjunctive D-cycloserine improved depressive symptoms in treatment-resistant depression and bipolar depression.
Sources: 1

Psilocybin (various formulations)

Sponsor: Multiple (academic/industry)
Phase: Phase 2/3
NCT: NCT06141876
Mechanism: Classic psychedelic (5-HT2A receptor agonist)
Side Effect Comparison: Psilocybin is not associated with sexual dysfunction, weight gain, or chronic sedation. Most side effects are acute (transient anxiety, headache, nausea) and resolve within hours to days. No evidence of dependence or withdrawal.
Efficacy Data:
- Response rate: Not specified in this trial; other psilocybin studies report 50-70% response
- Remission rate: Not specified in this trial; other psilocybin studies report 29-54% remission at 3-6 weeks
- MADRS change: Not specified; psilocybin has shown large effect sizes in TRD (e.g., -17.8 vs -5.4 placebo in other studies)
- Time to response: 1-2 days after dosing
- Source
Why it might interest you: Psilocybin offers a fundamentally different approach, with rapid and durable antidepressant effects after one or two sessions, and avoids the chronic side effects of standard antidepressants (sexual dysfunction, weight gain, emotional blunting).
Results: Psilocybin has demonstrated rapid and robust antidepressant effects in multiple studies, with effects lasting weeks to months after a single dose.
Sources: 1, 2

Appendix D: Methodology

We analyzed more than 30,000 clinical trial listings from ClinicalTrials.gov, over 300 research articles indexed in PubMed, and reviewed 51 online discussions. Alongside, 70 adverse events from the OpenFDA Drug Label were cross-referenced with 14 user-reported side effects. Severity, frequency, and user perspectives were synthesized, using representative quotations for a comprehensive and patient-centered view.