Paxil vs Zoloft

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For patients with major depressive disorder (MDD) or other types of depression, certain medications can help by modulating the levels of neurotransmitters in the brain that are linked to mood. Paxil and Zoloft are two such drugs that are often prescribed for these conditions. Both drugs work on serotonin, a neurotransmitter associated with feelings of well-being and happiness. Paxil, also known as paroxetine, is a selective serotonin reuptake inhibitor (SSRI), which means it works by increasing the availability of serotonin in the brain. Similarly, Zoloft, also known as sertraline, is another SSRI that operates on similar principles but might have different side effects or be more effective depending upon individual patient characteristics and responses.

What is Paxil?

Paroxetine (the generic name for Paxil) was a significant advancement in the class of drugs known as selective serotonin reuptake inhibitors (SSRIs), following the initial development of tricyclic antidepressants. Paxil was first approved by the FDA in 1992 and is used to increase levels of free serotonin by preventing it from being reabsorbed, in effect keeping it active within the brain for longer periods. It is prescribed for various forms of depression, anxiety disorders, obsessive-compulsive disorder, and post-traumatic stress disorder among others. Similar to fluoxetine's action on neurotransmitters, paroxetine majorly influences serotonin with only slight effects on dopamine and norepinephrine. This results in fewer side effects compared to other antidepressants that strongly affect these two additional neurotransmitters.

On the other hand, Sertraline (Zoloft) also belongs to SSRI group but differs slightly from paroxetine regarding its influence on certain types of receptors and uptake pumps which can lead to different side effect profiles between both medications.

What conditions is Paxil approved to treat?

Paxil is approved for the treatment of a variety of mental health disorders, including:

  • Major depressive disorder (MDD)
  • Panic disorder with or without agoraphobia
  • Social anxiety disorder (SAD)
  • Generalized Anxiety Disorder (GAD)
  • Post-traumatic stress disorder (PTSD)
  • Obsessive-compulsive disorder (OCD).

How does Paxil help with these illnesses?

Paxil works to manage depression by increasing the amount of serotonin available in the synapses of the brain, similar to Prozac. It does this by inhibiting its reabsorption into the neurons, allowing for higher levels of serotonin to be maintained for longer periods. Serotonin is a neurotransmitter that contributes significantly to mood regulation, cognitive function, memory consolidation, sleep patterns and appetite control among other functions. There's a consensus within medical circles that individuals suffering from depression typically have lower serotonin levels than average. As such, by facilitating an increase in serotonin concentration within synaptic gaps, Paxil can help mitigate negative depressive symptoms and assist patients in managing their condition and stabilizing their moods.

Similarly Zoloft also increases the level of serotonin in your brain but it has less side effects on weight gain or sexual dysfunction as compared to Paxil which makes it preferable choice for many patients struggling with depression.

What is Zoloft?

Zoloft, a brand name for sertraline, is a selective serotonin reuptake inhibitor (SSRI) that functions by increasing the levels of serotonin in the brain by reducing its reabsorption. It also minimally inhibits dopamine and norepinephrine uptake. Sertraline was first approved by the FDA in 1991. Unlike other antidepressants such as Paxil (paroxetine), Zoloft does not have significant effects on other neurotransmitters which result in less side effects like sedation, weight gain or sexual dysfunction commonly associated with these drugs. Its favorable side-effect profile makes it an attractive option for patients considering SSRI treatment options for depression and anxiety disorders. The effect on serotonin can be beneficial especially to those who respond well to increased serotonin levels compared to “atypical” antidepressant drugs such as Paxil.

What conditions is Zoloft approved to treat?

Zoloft is a selective serotonin reuptake inhibitor (SSRI) that has been approved for the treatment of:

  • Major depressive disorder (MDD)
  • Obsessive-compulsive disorder (OCD)
  • Panic disorder
  • Posttraumatic stress disorder (PTSD)
  • Social anxiety disorder Additionally, Zoloft can also be used to treat premenstrual dysphoric disorder.

How does Zoloft help with these illnesses?

Serotonin is a neurotransmitter known as the "feel good" hormone, playing pivotal roles in mood regulation, sleep cycle, and appetite control. Low levels of serotonin have been associated with depression and anxiety disorders. Zoloft operates by increasing the levels of serotonin accessible in the brain, thereby alleviating some symptoms related to these mental health conditions. Its action on dopamine may also play a part in its overall antidepressant effect. Unlike Paxil which has more sedative effects and can lead to weight gain, Zoloft does not significantly affect norepinephrine or histamine receptors making it an appealing choice for patients who don't respond well to other SSRIs or are concerned about certain side-effects like drowsiness or increased appetite.

How effective are both Paxil and Zoloft?

Both paroxetine (Paxil) and sertraline (Zoloft) are selective serotonin reuptake inhibitors, or SSRIs, with established histories of success in treating patients with depression. They were initially approved by the FDA within a few years of each other – Paxil in 1992 and Zoloft in 1991. Since they act on the same neurotransmitter system - primarily enhancing serotonin signaling - they may be prescribed under similar circumstances.

In terms of their effectiveness for depression, both have been directly compared in multiple double-blind clinical trials over the past few decades; these two drugs exhibit comparable efficacy in managing symptoms of depression as well as similar safety profiles. In most studies comparing them head-to-head, no significant differences have been found between Paxil and Zoloft when it comes to overall improvement rates for depressive symptoms.

A 2006 review article reported that paroxetine is effective from the first week of treatment at alleviating symptoms of major depressive disorder (MDD), panic disorder (PD), social anxiety disorder (SAD), generalized anxiety disorder (GAD), post-traumatic stress disorder (PTSD) and obsessive-compulsive disorder (OCD). Its side effect profile is generally favorable compared to older antidepressants like tricyclics or monoamine oxidase inhibitors, although some people do experience common SSRI-related side effects such as sexual dysfunction or weight changes.

On the other hand, a large meta-analysis published in The Lancet journal showed that sertraline appears to be slightly better tolerated than paroxetine – meaning fewer patients stop taking it due to adverse events – while being equally effective for major psychiatric disorders including MDD, PD, SAD, GAD and PTSD. Like all SSRIs though, there can still be potential side effects such as gastrointestinal upset and sleep disturbances.

abstract image of a researcher studying a bottle of drug.

At what dose is Paxil typically prescribed?

Oral dosages of Paxil range from 20–50 mg/day, but research suggests that a dosage of 20 mg/day is generally sufficient for treating major depressive disorder in most adults. For children and adolescents with obsessive-compulsive disorder, the recommended starting dose is 10 mg per day. In either population, dosage can be increased after several weeks if there is no significant response or improvement. The maximum dosage that should not be exceeded under any circumstance for adults is 60 mg/day and for children and adolescents it's 50mg/day.

Zoloft, on the other hand, has a broader range of dosages varying from condition to condition. For depression and obsessive-compulsive disorder in adults it ranges between 50-200mg while in children it starts at a much lower dose around 25mg. It's crucial that all changes are made gradually under medical supervision to avoid adverse effects.

At what dose is Zoloft typically prescribed?

Zoloft treatment typically begins at a dosage of 50 mg/day, which can be taken with or without food. If necessary, the dose may then be increased to a maximum of 200 mg/day, depending on the patient's response and tolerance. This increase should occur in increments no greater than 50 mg per week over a period of several weeks. The medication is generally administered once daily, either in the morning or evening according to personal preference and lifestyle considerations. It's important to note that changes in depression symptoms might not become apparent until after four weeks or more from the start of treatment.

What are the most common side effects for Paxil?

Common side effects of Paxil and Zoloft may include:

  • Anxiety or nervousness
  • Insomnia (trouble sleeping)
  • Somnolence (excessive sleepiness/drowsiness)
  • Asthenia (generalized weakness or lack of energy)
  • Tremor (shaky movements that you can't control)
  • Nausea, upset stomach, diarrhea
  • Dry mouth
  • Decreased sex drive, impotence, abnormal ejaculation in males
  • Sweating more than usual
  • Possible weight changes: gain for Paxil users; loss for those on Zoloft.

Less common but serious effects could be unusual bleeding/bruising and persistent nausea/vomiting. Always consult your healthcare provider if you're experiencing these symptoms persistently.

abstract image of a patient experiencing side effect

Are there any potential serious side effects for Paxil?

While both Paxil and Zoloft are selective serotonin reuptake inhibitors used to treat depression, their side effects can differ:

  • Increased suicidal thoughts or behaviors: This is a risk particularly in people under 25 when they first start taking the medication.
  • Allergic reactions: Symptoms may include rash, itching/swelling (especially of the face/tongue/throat), severe dizziness, trouble breathing.
  • Vision changes: Instances of blurred vision, eye pain or swelling or seeing halos around lights could suggest a serious eye problem.
  • Heart issues: Rapid heart rate, chest fluttering or feeling like you're about to faint can indicate cardiovascular problems.
  • Sodium levels: Low sodium levels in your body could also lead to a headache, confusion, slurred speech, severe weakness, vomiting and unsteadiness. -Severe nervous system reaction - Symptoms such as rigid muscles high fever sweating confusion fast or uneven heartbeats tremors might indicate an adverse nervous system reaction -Serotonin Syndrome is rare but very serious. Look out for symptoms like hallucinations extreme restlessness fever rapid heartbeat muscle stiffness twitching loss of coordination nausea vomiting diarrhea.

If you experience any of these symptoms while on either Paxil or Zoloft seek immediate medical attention.

What are the most common side effects for Zoloft?

Potential side effects of Zoloft can include:

  • Dry mouth, or increased saliva production
  • Stomach upset such as nausea, vomiting and diarrhea
  • Decreased appetite leading to weight loss
  • Sleep problems including insomnia or excessive sleepiness
  • Sweating more than usual
  • Feeling nervous, shaky or agitated
  • A faster heartbeat than normal
  • Dizziness and feeling faint
  • Muscle pain or spasms and joint stiffness
  • Skin rashes that may be itchy

Are there any potential serious side effects for Zoloft?

Zoloft, like any other medication, has the potential to cause side effects. Certain symptoms might indicate a serious condition and should prompt immediate medical attention. These include:

  • Signs of an allergic reaction such as skin rash or hives; difficulty breathing; swelling of your face, lips, tongue, or throat.
  • Unusual changes in mood or behavior including new or worsening depression; anxiety; panic attacks; feelings of agitation, restlessness, irritability.
  • Symptoms suggestive of serotonin syndrome: hallucinations, fast heart rate, fever, overactive reflexes,tremors.
  • Blurred vision
  • Heart problems such as chest pain and fast/irregular heartbeat
  • Severe nausea,vomiting or diarrhea
  • Changes in weight or appetite.

If you experience any of these side effects while taking Zoloft , contact your healthcare provider immediately.

Contraindications for Paxil and Zoloft?

Both Paxil and Zoloft, like most other selective serotonin reuptake inhibitor (SSRI) antidepressants, may exacerbate symptoms of depression in certain individuals. If you observe an increase in your depressive symptoms or a rise in thoughts or behaviors of self-harm, it's crucial to seek immediate medical attention.

Neither Paxil nor Zoloft should be taken if you are using monoamine oxidase inhibitors (MAOIs), another class of antidepressants. It is essential to inform your doctor about all the medications you're currently taking; MAOIs require approximately 5 weeks to completely clear from your system to avoid dangerous interactions with both Paxil and Zoloft. Also, abruptly stopping either medication can lead to withdrawal effects; hence it's best done under medical supervision.

How much do Paxil and Zoloft cost?

For brand name versions of these drugs:

  • The price for 30 tablets of Paxil (20 mg) averages around $130, which works out to approximately $4.33/day.
  • The price for a similar number of Zoloft tablets (50 mg) is around $330, working out to about $11/day.

Thus, if you are taking equal dosages, then brand-name Paxil is less expensive on a per-day treatment basis than Zoloft. However, cost should not be the primary consideration in determining which of these drugs is right for you.

As for generic versions - paroxetine (Paxil) and sertraline (Zoloft), costs are significantly lower:

  • Paroxetine costs range from $0.10 to $0.80 per day depending on your dose and the pharmacy.
  • Sertraline ranges between about $0.15 and up to a dollar or so per day depending again on dosage and where it's purchased.

Remember that prices can vary based on your location, insurance coverage, and where you purchase the medication from.

Popularity of Paxil and Zoloft

Paroxetine, available as a generic and under the brand name Paxil, was prescribed to about 4 million people in the US in 2020. Paroxetine accounted for just over 10% of SSRI prescriptions in the US. It's part of a class of drugs known as selective serotonin reuptake inhibitors (SSRIs), which are commonly used to treat depression. Over time, prescriptions for paroxetine have been gradually declining since its peak usage around 2002.

Sertraline, sold under the brand name Zoloft among others, was prescribed to approximately 8 million individuals in America during 2020. In terms of SSRI prescriptions within the country, sertraline holds a significant share at roughly 25%. As one of the most frequently used antidepressants overall — encompassing up to about 15% of total U.S antidepressant prescriptions — sertraline has maintained fairly consistent usage rates throughout this past decade.


Both Paxil (paroxetine) and Zoloft (sertraline) have a long-standing history of usage in treating conditions such as depression, anxiety disorders, obsessive-compulsive disorder, and post-traumatic stress disorder. They are both selective serotonin reuptake inhibitors (SSRIs), with their efficacy backed by numerous clinical studies and meta-analyses indicating that they are more effective than placebo treatments.

Due to their similar mechanisms of action—primarily increasing the level of serotonin in the brain—they may be prescribed under different circumstances based on each patient's individual needs and responses. While both drugs can be first-line treatment options for these conditions, Paxil is often reserved for patients who do not respond well to other SSRI medications due to its slightly higher risk profile.

Both drugs are available in generic form which represents significant cost savings especially for patients who must pay out-of-pocket. An adjustment period may be required when starting either medication; meaning effects might not be noticeable right away.

The side effect profiles between Paxil and Zoloft are relatively comparable—with nausea, dry mouth, drowsiness being common—but Paxil has been associated more frequently with weight gain and sexual dysfunction compared to Zoloft. As with all SSRIs, it's important for patients starting on these medications to closely monitor their moods and seek medical help immediately if they notice worsening depression or suicidal thoughts.