Sudafed vs Allegra

Listen to the article instead of reading through it.


For individuals suffering from allergies or common cold symptoms, certain medications alter the concentration of compounds in the body that are linked to immune response and inflammation. Sudafed and Allegra are two such drugs commonly used for these ailments. They each impact different aspects of the body's immune response but both have symptom-relieving effects in patients with allergies or colds. Sudafed is a decongestant, working primarily by narrowing blood vessels to reduce swelling and congestion in the nasal passages. On the other hand, Allegra (fexofenadine) falls under antihistamines classification, functioning by blocking histamine - a substance produced during an allergic reaction - thereby relieving allergy symptoms like itchy eyes/nose/throat, runny nose and sneezing.

What is Sudafed?

Pseudoephedrine (the generic name for Sudafed) was one of the first drugs from a class known as nasal decongestants, which marked a significant development over earlier treatments for congestion. Pseudoephedrine was first approved by the FDA in 1951. Sudafed works by narrowing blood vessels to decrease swelling and congestion in the nasal passages, effectively reducing symptoms associated with common colds or allergies. It is prescribed for relieving stuffy nose and sinus caused by allergies, hay fever or the common cold.

On the other hand, Fexofenadine (sold under brand name Allegra among others) belongs to a newer generation of antihistamines that selectively inhibits peripheral H1 receptors. This results in it having fewer side effects than older antihistamines that can pass through the blood-brain barrier and cause drowsiness. These two medications have different modes of action: while Sudafed targets congestive symptoms directly, Allegra works by blocking histamine- an organic compound involved in local immune responses and acting as a neurotransmitter.

What conditions is Sudafed approved to treat?

Sudafed is approved for the treatment of various nasal congestion symptoms:

  • Nasal congestion due to common cold
  • Nasal congestion associated with sinusitis
  • Nasal congestion linked to allergies

On the other hand, Allegra (fexofenadine) is primarily indicated for:

  • Seasonal allergic rhinitis, also known as hay fever
  • Chronic idiopathic urticaria, or hives that have no identifiable cause

How does Sudafed help with these illnesses?

Sudafed works to alleviate nasal congestion by constricting the blood vessels in the lining of the nose, reducing swelling and thus opening up the nasal passages. It does this by stimulating alpha-adrenergic receptors throughout the body, which is part of your body's natural fight or flight response. This results in vasoconstriction (narrowing) of those blood vessels, hence relieving symptoms like stuffy nose associated with colds or allergies.

Allegra on the other hand acts as a histamine antagonist and binds to certain sites called H1 receptors in your body preventing histamines from carrying out their functions such as causing inflammation and increasing permeability of capillaries leading to symptoms like runny nose, sneezing etc.

Although both drugs are used for relief during allergy season or common colds they work differently; Sudafed directly targets decongestion while Allegra primarily helps by blocking histamines that cause allergic reactions.

What is Allegra?

Allegra, also known by its generic name fexofenadine, is an antihistamine used to alleviate the symptoms of seasonal allergies and chronic urticaria (hives). It works by blocking histamine receptors in the body, reducing allergic reactions. Fexofenadine was first approved by the FDA in 1996. Unlike Sudafed (pseudoephedrine), which acts as a decongestant and can cause restlessness or insomnia, Allegra does not have a stimulating effect on the central nervous system. Consequently, it is less likely to cause sleep disturbances or feelings of jitteriness. Furthermore, unlike some other antihistamines, Allegra does not cross into the brain from the blood and therefore has fewer side effects related to sedation and drowsiness - common issues with older generation antihistamines like Diphenhydramine (Benadryl). This makes Allegra a more attractive choice for those needing relief from allergy symptoms without unwanted side effects.

What conditions is Allegra approved to treat?

Allegra is FDA approved for the treatment of:

  • Seasonal Allergic Rhinitis, also known as hay fever
  • Chronic Idiopathic Urticaria, more commonly referred to as hives.

Unlike Sudafed, Allegra does not cause sleepiness and has minimal side effects such as occasional headaches or an upset stomach. It's a reliable choice for those seeking relief from allergy symptoms without the drowsiness associated with other medications.

How does Allegra help with these illnesses?

Histamine is a compound that's released by cells in response to injury and allergic or inflammatory reactions, leading to contraction of smooth muscle and dilation of capillaries. It plays crucial roles in many allergic responses. Allegra (fexofenadine) works by blocking the action of histamine on certain receptors (H1-receptors), thereby alleviating some symptoms associated with allergies such as sneezing, runny nose, itching eyes/nose, hives, and rashes. Unlike Sudafed which primarily acts as a decongestant affecting nasal passages directly through vasoconstriction effects, Allegra has an antihistaminic action making it more effective for a broad range of allergy symptoms. Its non-drowsy formulation also gives it an advantage over other first-generation antihistamines when it comes to side effect profile. Therefore, if patients are looking for relief from multiple allergy symptoms without the sedative effects common with older drugs or direct decongestion pathway like Sudafed employs but rather want systemic control over their allergic response may find Allegra more suitable.

How effective are both Sudafed and Allegra?

Both pseudoephedrine (Sudafed) and fexofenadine (Allegra) have proven effective in treating symptoms associated with allergies, such as nasal congestion and hives. Approved by the FDA only a few years apart, Sudafed in 1976 and Allegra in 1996, they act on different aspects of the body's immune response to allergens.

Pseudoephedrine works primarily as a decongestant by constricting blood vessels in the nasal passages whereas fexofenadine acts as an antihistamine by blocking histamines from binding to cells. A direct comparison between these two drugs was conducted through a randomized controlled trial in 2001 where patients took either drug for two weeks. The study found that both medications had similar efficacy when it came to relieving allergy symptoms, although Sudafed was more effective at reducing nasal congestion while Allegra excelled at controlling sneezing and itching.

A meta-analysis published in 2012 highlighted that fexofenadine is not only helpful for managing allergic rhinitis but also chronic idiopathic urticaria starting from the first week of treatment; its side effect profile is favorable over many other antihistamines due to its non-drowsy formula. It’s been noted that Fexofenadine has become one of the most widely used antihistamine drugs across the globe thanks to both its effectiveness and safety record.

On another note, Sudafed continues to be a go-to option for instant relief of sinus pressure and stuffiness related issues due to seasonal or perennial allergies. Although considered safe overall, it can lead to side effects like insomnia or nervousness because of its stimulant properties which means care should be taken especially among individuals prone to anxiety or sleep disorders.

abstract image of a researcher studying a bottle of drug.

At what dose is Sudafed typically prescribed?

Oral dosages of Sudafed for adults and children 12 years and older range from 60-120 mg every 4 to 6 hours, with the maximum daily dose not exceeding 240 mg per day. For Allegra, adults and children aged 12 years and above should take a dosage of either one tablet (180mg) once daily or half a tablet (90mg) twice daily. Children aged between six to eleven can start on half the adult dosage. In both cases, if there is no response after taking these medications for a few days, consult your healthcare provider for advice. It's important that the maximum recommended dosages are not exceeded in any situation.

At what dose is Allegra typically prescribed?

Allegra, also known as Fexofenadine, is typically recommended at a dosage of 60 mg twice daily or 180 mg once daily for adults and children aged 12 years and older. For children between the ages of 6 to 11 years old, a reduced dose of 30 mg twice daily is advised. The effects generally start within two hours after administration and can last up to twenty-four hours. Thus, it's crucial not to exceed the maximum recommended daily dose in order to avoid side effects. If there are no noticeable improvements after a few weeks of treatment with Allegra at these dosages, you should consult your healthcare provider for further evaluation.

What are the most common side effects for Sudafed?

Common side effects of Sudafed include:

  • Restlessness or anxiety
  • Nervousness, excitement (especially in children)
  • Dizziness, headache
  • Insomnia (difficulty sleeping)
  • Mild tremors
  • Skin rash
  • Dry mouth or throat, thirst
  • Reduced appetite
  • Nausea or vomiting

On the other hand, Allegra is known to cause:

  • Headache
  • Back pain
  • Coughing
  • Diarrhea
  • Painful menstruation

abstract image of a patient experiencing side effect

Are there any potential serious side effects for Sudafed?

Although Sudafed and Allegra are both used to treat allergy symptoms, they can have different side effects. The potential serious side effects of Sudafed include:

  • Severe allergic reactions such as skin rash, itching or hives, swelling of the face, lips or tongue
  • Fast or irregular heartbeats
  • Hallucinations and severe restlessness
  • Unusual fever or chills
  • Severe dizziness or fainting spells

On the other hand, serious but less common side effects related to Allegra may involve:

  • Allergic reaction like skin rash, itching or hives; swelling of the face, lips or tongue
  • Breathing problems
  • Rapid heartbeat
  • Fever
  • Feeling faint

If you experience any of these symptoms whether you're taking Sudafed or Allegra it's important that you stop using the medication and seek immediate medical attention.

What are the most common side effects for Allegra?

Similar to other antihistamines, Allegra (Fexofenadine) can cause some mild side effects which include:

  • Headache or dizziness
  • Nausea, diarrhea
  • Coughing, dry mouth or throat
  • Painful menstruation in women
  • Drowsiness and fatigue

However, unlike Sudafed which may result in significant sleep problems like insomnia due to its stimulant properties, the incidence of this issue is significantly less with Allegra. Moreover, while both drugs might induce a feeling of nervousness or anxiety in some individuals due to their influence on histamine pathways that regulate mood and stress responses, these symptoms are generally more pronounced with Sudafed rather than Allegra. Lastly it's worth noting that although rare cases of skin rash have been reported for both medications; the odds are higher when taking Sudafed compared to using Allegra.

Are there any potential serious side effects for Allegra?

Although Allegra is known for its efficiency in managing allergy symptoms, it's not devoid of potential side effects. These rare but serious side effects include:

  • Signs of an allergic reaction like rash, itching or hives on the skin; swelling of the face, lips, tongue or other parts of the body; shortness of breath, wheezing or trouble breathing.
  • Symptoms such as rapid heartbeat and flushing
  • A feeling that your heart is pounding or racing (palpitations)
  • Dizziness, spinning sensation
  • Trouble sleeping (insomnia)
  • Nervousness

If you experience any unusual changes after taking Allegra such as mood alterations or confusion, ensure to contact your healthcare provider immediately. Additionally, while very unlikely with antihistamines like Allegra if you have thoughts about self-harm reach out to a mental health professional right away.

Contraindications for Sudafed and Allegra?

Allegra and Sudafed, like most other allergy medications, may worsen symptoms of certain conditions in some individuals. If you notice an increase in dizziness, insomnia or palpitations after taking these medicines, please seek immediate medical attention.

Neither Allegra nor Sudafed should be taken if you are consuming monoamine oxidase (MAO) inhibitors. Always inform your physician about all the medications that you're currently taking; MAOIs will require a period of about 2 weeks to clear from the system to prevent dangerous interactions with Allegra and Sudafed.

Moreover, both drugs can raise blood pressure so they should be used with caution in patients with hypertension. With Sudafed specifically, there's a risk for overstimulation leading to restlessness or insomnia which is less common with Allegra.

How much do Sudafed and Allegra cost?

For the brand name versions of these drugs:

  • The price of 48 tablets of Sudafed (30 mg) averages around $12, which works out to approximately $0.25/day, depending on your dose.
  • The price of 30 tablets of Allegra (180 mg) is about $20, working out to approximately $0.67/day.

Thus, if you are in the higher dosage range for Sudafed (i.e., 60 mg/day or higher), then brand-name Allegra is less expensive on a per-day treatment basis. Please note that cost should not be a primary consideration in determining which of these drugs is right for you.

In terms of generic versions:

  • Pseudoephedrine hydrochloride (Sudafed's active ingredient; 30mg tablets) can be found at prices as low as $3 for packs up to 36 capsules ($0.08-$0.25 per day).
  • Fexofenadine HCl (Allegra's active ingredient; 180mg tablets) comes in packs starting from ten tablets and above with costs varying between roughly $6 and upwards ($0.20-$1+ per day). As always, prices will vary based on supplier and quantity purchased.

Popularity of Sudafed and Allegra

Pseudoephedrine, both in generic form and under brand names such as Sudafed, was estimated to have been purchased by about 7 million people in the US in 2020. Pseudoephedrine accounted for a significant portion of over-the-counter decongestant purchases in the US. This drug is commonly used for its quick relief from nasal congestion related to colds or allergies.

Fexofenadine, including brand versions such as Allegra, was utilized by approximately 5 million people in the USA in 2020. In the US market, fexofenadine accounts for a substantial share of antihistamine purchases and prescriptions. It is widely known for its non-drowsy formulation that effectively manages seasonal allergy symptoms without causing any sedative effects. The use of Fexofenadine has seen steady prevalence over recent years due to its effectiveness and minimal side effects compared to first-generation antihistamines.


Both Sudafed (pseudoephedrine) and Allegra (fexofenadine) have a long history of effective use in relieving symptoms associated with allergies such as runny nose, sneezing, itchy or watery eyes, and itching of the nose or throat. Both are supported by numerous clinical studies demonstrating their effectiveness over placebo treatments. In some cases, these drugs may be used together to manage severe symptoms due to their different mechanisms: Sudafed acts primarily as a decongestant while Allegra is an antihistamine.

Sudafed is typically used for short-term relief from nasal congestion due to common colds or allergies, whereas Allegra would generally be considered for regular use during allergy season or for chronic hives without a known cause.

Both medications are available in generic form which can represent significant cost savings particularly for patients who must pay out-of-pocket. The effects of both Sudafed and Allegra are often felt quickly but can vary per individual.

The side effect profile is relatively similar between the two drugs; they're generally well-tolerated but come with potential concerns. Sudafed could increase blood pressure making it less suitable than Allegra for people with hypertension. For any medication, patients should monitor their responses when starting treatment and consult healthcare professionals if adverse reactions occur.