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Medical Disclaimer: This information is for educational purposes only and is not a substitute for professional medical advice.
Brand Name
Allegra Allergy 24 Hour
Generic Name
Fexofenadine Hydrochloride
Active Ingredient
FexofenadineCategory
Other
Salt Form
Hydrochloride
Variants
1
Different strengths and dosage forms
| Strength | Form | Route | NDC |
|---|---|---|---|
| 180 mg/1 | TABLET, FILM COATED | ORAL | 85237-0190 |
Detailed information about Allegra Allergy 24 Hour
This page is for informational purposes only and does not replace medical advice. Before using any prescription or over-the-counter medication for Allegra Allergy 24 Hour, you must consult a qualified healthcare professional.
Fexofenadine is a second-generation H1-antihistamine used to treat seasonal allergic rhinitis and chronic idiopathic urticaria. It is known for its non-sedating properties compared to first-generation antihistamines.
For the treatment of seasonal allergic rhinitis and chronic idiopathic urticaria in adults and adolescents (12 years of age and older), the standard recommended dosages are as follows:
Clinical trials have shown that the 180 mg once-daily dose provides 24-hour coverage, making it a convenient option for most patients. The 60 mg twice-daily regimen may be preferred by some healthcare providers to maintain more consistent plasma levels throughout the day.
Fexofenadine dosing in children is highly dependent on age and the condition being treated. According to clinical guidelines:
Because fexofenadine is partially cleared by the kidneys, patients with decreased kidney function require dosage modifications. For adults with renal impairment, the recommended starting dose is 60 mg once daily. For pediatric patients with renal impairment, the starting dose should be reduced (e.g., for children 2-11 years, 30 mg once daily instead of twice daily).
Since fexofenadine undergoes minimal hepatic metabolism, dosage adjustments are generally not required for patients with liver disease. However, a complete medical evaluation is always necessary.
Clinical studies have shown that fexofenadine concentrations are higher in elderly patients due to age-related declines in renal function. Healthcare providers typically start elderly patients at the lower end of the dosing range (60 mg once daily) and monitor for side effects.
To ensure maximum efficacy and safety, patients should follow these specific administration instructions:
If you miss a dose of fexofenadine, take it as soon as you remember. If it is almost time for your next scheduled dose, skip the missed dose and resume your regular dosing schedule. Do not take two doses at once to make up for a missed one, as this increases the risk of side effects.
While fexofenadine has a wide safety margin, an overdose can occur. Reported symptoms of fexofenadine overdose include dizziness, drowsiness, and dry mouth. In the event of a suspected overdose, contact your local poison control center or seek emergency medical attention immediately. Treatment typically involves supportive care, as fexofenadine is not effectively removed by hemodialysis.
> Important: Follow your healthcare provider's dosing instructions exactly. Do not adjust your dose or stop taking the medication without medical guidance, especially if you are using it for chronic conditions like urticaria.
Fexofenadine is generally well-tolerated, and many patients experience no side effects at all. However, in clinical trials, the most frequently reported adverse effect was:
These side effects may occur in a small percentage of the population. While not usually serious, they can be bothersome:
These effects are infrequent but have been documented in post-marketing surveillance:
While extremely rare, serious reactions can occur. You should stop taking the medication and contact a doctor immediately if you experience:
> Warning: Stop taking Fexofenadine and call your doctor immediately if you experience any of these.
Fexofenadine is often used for months or even years by patients with chronic allergies or hives. Current clinical data suggests that there are no significant cumulative toxicities associated with long-term use. It does not appear to cause organ damage (such as liver or kidney toxicity) in healthy individuals when taken at recommended doses. However, patients should have their renal function monitored periodically, especially as they age, to ensure that the dosage remains appropriate for their clearance levels.
There are currently no FDA black box warnings for fexofenadine. Unlike its predecessor terfenadine, fexofenadine does not cause dangerous heart rhythm disturbances (torsades de pointes) when taken with other medications that inhibit liver enzymes. This safety profile is the primary reason fexofenadine is available over-the-counter in many regions.
Report any unusual symptoms or persistent side effects to your healthcare provider. Even mild side effects can sometimes be managed by adjusting the timing of the dose or switching to a different formulation.
Fexofenadine is widely regarded as one of the safest antihistamines available. However, 'safe' does not mean 'risk-free.' Patients must be aware that the effectiveness and safety of the drug depend on proper usage and the disclosure of all underlying health conditions to a healthcare provider. The most significant concern for most patients is the interaction with fruit juices, which can render the medication much less effective. Additionally, while it is non-sedating for the vast majority of people, individual responses vary, and caution should be exercised when first starting the drug.
No FDA black box warnings for Fexofenadine. It has a high safety profile and was specifically developed to avoid the cardiac risks associated with older drugs in its class.
For the average healthy adult taking fexofenadine for seasonal allergies, routine laboratory monitoring is generally not required. However, for specific populations:
Fexofenadine is classified as non-sedating. Clinical studies involving driving simulators and actual road tests have shown that fexofenadine at the 180 mg dose does not impair driving performance. However, because a very small percentage of people may experience drowsiness or dizziness, it is prudent to observe how the medication affects you before driving or operating heavy machinery for the first time.
While fexofenadine does not typically potentiate (increase) the sedative effects of alcohol in the same way that first-generation antihistamines (like diphenhydramine) do, it is still generally advised to limit alcohol consumption. Combining any medication with alcohol can increase the risk of dizziness or gastrointestinal upset.
Fexofenadine does not require a tapering period. You can typically stop taking it 'cold turkey' without experiencing withdrawal symptoms. However, if you are taking it for chronic hives or severe allergies, your symptoms may return once the medication is out of your system (usually within 2-3 days). If you experience a significant 'rebound' of itching or sneezing, consult your doctor about a long-term management strategy.
> Important: Discuss all your medical conditions, especially kidney disease, with your healthcare provider before starting Fexofenadine. Always provide a full list of other medications you are taking to avoid potential complications.
There are no absolute 'never-use' contraindications for fexofenadine in the same way there are for some high-risk drugs. However, the use of fexofenadine with Terfenadine is contraindicated because fexofenadine is the metabolite of terfenadine, and taking both would lead to an unpredictable and potentially dangerous accumulation of the drug.
> Important: Tell your doctor about ALL medications, supplements, and herbal products you are taking. Even over-the-counter supplements can change how fexofenadine works in your body.
There are very few absolute contraindications for fexofenadine, which contributes to its status as a widely used over-the-counter medication. However, it must NEVER be used in the following circumstances:
These are conditions where the drug should be used only if the potential benefit outweighs the risk, and under close medical supervision:
There is no significant evidence of cross-sensitivity between fexofenadine and other classes of antihistamines (like the ethanolamines or ethylenediamines). However, patients sensitive to one second-generation antihistamine (like loratadine or cetirizine) should still monitor their response to fexofenadine closely, as inactive ingredients in the tablets often overlap.
> Important: Your healthcare provider will evaluate your complete medical history, including your kidney health and any previous drug allergies, before prescribing Fexofenadine. Always read the 'Drug Facts' label on over-the-counter products.
Fexofenadine was previously classified under FDA Pregnancy Category C. This means that animal reproduction studies have shown an adverse effect on the fetus, but there are no adequate and well-controlled studies in humans. Specifically, in animal studies, fexofenadine was associated with decreased pup weight and decreased survival when administered at doses many times higher than the human therapeutic dose.
Clinical Guidance: Healthcare providers generally recommend that fexofenadine be used during pregnancy only if the potential benefit justifies the potential risk to the fetus. Many clinicians prefer using other antihistamines with more extensive human safety data (such as loratadine or cetirizine) as first-line options for pregnant patients.
Data on the excretion of fexofenadine in human milk is limited. However, because fexofenadine is a large molecule and is highly protein-bound, it is expected that only small amounts would pass into breast milk.
Clinical Guidance: Fexofenadine is generally considered compatible with breastfeeding by many experts because it is non-sedating and unlikely to affect the nursing infant's alertness or milk supply. However, as with all medications, nursing mothers should consult their pediatrician before use. Monitor the infant for any unusual sleepiness or irritability.
Fexofenadine is approved for use in children as young as 6 months for chronic idiopathic urticaria and 2 years for seasonal allergic rhinitis.
In patients aged 65 and older, peak plasma levels of fexofenadine can be up to 99% higher than in younger patients. This is primarily due to the natural decline in renal (kidney) function that occurs with age.
The pharmacokinetics of fexofenadine are significantly altered in patients with kidney disease. In patients with mild to moderate impairment, the half-life can increase from 14 hours to nearly 20 hours.
Because fexofenadine is not significantly metabolized by the liver, no dosage adjustments are required for patients with hepatic impairment (liver disease). This makes it a safer choice for patients with cirrhosis compared to antihistamines that require extensive hepatic processing.
> Important: Special populations require individualized medical assessment. Always consult with a specialist (obstetrician, pediatrician, or nephrologist) when using Fexofenadine in these specific groups.
Fexofenadine hydrochloride is a second-generation, selective peripheral H1-receptor antagonist. Its primary molecular mechanism involves binding to the H1 receptor, which is a G protein-coupled receptor. Specifically, fexofenadine acts as an inverse agonist. This means it does not just block histamine from binding; it actively binds to the receptor and stabilizes it in its inactive state. This prevents the downstream signaling that leads to the release of pro-inflammatory cytokines and the physiological symptoms of allergy (itching, swelling, and mucus production).
Crucially, fexofenadine has a very low affinity for muscarinic, cholinergic, or alpha-adrenergic receptors. This selectivity is why it does not cause the 'dry eyes' or 'dry mouth' (anticholinergic effects) common with older antihistamines. Furthermore, fexofenadine is a substrate for the P-glycoprotein (P-gp) efflux transporter, which actively pumps the drug out of the brain, ensuring that CNS concentrations remain extremely low.
| Parameter | Value |
|---|---|
| Bioavailability | ~33% |
| Protein Binding | 60% - 70% (Albumin & Acid Glycoprotein) |
| Half-life | 14.4 hours |
| Tmax | 2.6 hours |
| Metabolism | Minimal (<5% hepatic) |
| Excretion | Fecal 80%, Renal 11% |
Fexofenadine is classified as a Second-Generation Antihistamine. It belongs to the piperidine subclass. Related medications in this class include loratadine (Claritin), cetirizine (Zyrtec), and desloratadine (Clarinex). Among these, fexofenadine is often cited as having the lowest potential for sedation at standard doses.
Common questions about Allegra Allergy 24 Hour
Fexofenadine is primarily used to relieve symptoms of seasonal allergic rhinitis, commonly known as hay fever, in adults and children. These symptoms include sneezing, runny nose, itchy throat, and red, itchy, or watery eyes. Additionally, it is FDA-approved to treat chronic idiopathic urticaria, which are long-lasting hives that occur without a known cause. It works by blocking histamine, a substance in the body that causes allergic reactions. Because it is a second-generation antihistamine, it provides this relief without the significant drowsiness associated with older allergy medications. Your healthcare provider may also suggest it for other minor allergic skin conditions.
The most common side effect reported by patients taking fexofenadine is a mild headache, occurring in about 7% to 10% of users. Other relatively frequent side effects include dizziness, nausea, and a feeling of sleepiness, although the latter is rare compared to other antihistamines. Some individuals may also experience stomach upset or menstrual cramps. Most of these symptoms are temporary and go away as your body becomes accustomed to the medication. If these effects persist or become bothersome, you should consult your doctor. Serious side effects are extremely rare but require immediate medical attention.
Generally, it is best to avoid or limit alcohol consumption while taking any antihistamine, including fexofenadine. While fexofenadine is specifically designed to be non-sedating and does not typically interact with alcohol as severely as older drugs like diphenhydramine, the combination can still increase the risk of dizziness or impaired coordination in some people. Alcohol can also worsen certain allergy symptoms or contribute to dehydration. If you choose to drink, do so in moderation and observe how the medication affects you first. Always discuss your alcohol intake with your healthcare provider to ensure it is safe for your specific health profile.
Fexofenadine is generally used during pregnancy only if the potential benefits outweigh the potential risks to the fetus. It was previously categorized by the FDA as a Category C medication, meaning animal studies showed some risks but human data is limited. Many doctors prefer to prescribe other antihistamines like loratadine or cetirizine for pregnant women because those drugs have a longer history of documented safety in human pregnancies. If you are pregnant or planning to become pregnant, you must discuss your allergy management with your obstetrician. They will help you weigh the severity of your symptoms against the available safety data. Never start a new medication during pregnancy without professional medical guidance.
Fexofenadine is known for its relatively fast onset of action, with most patients beginning to feel relief within 1 to 2 hours after taking a dose. The medication reaches its peak concentration in the bloodstream approximately 2 to 3 hours after administration. Its effects are long-lasting, typically providing relief for a full 12 to 24 hours depending on the specific strength you are taking. For the best results, it should be taken consistently as directed by your healthcare provider or the product packaging. If you do not feel any improvement in your symptoms after a few days of use, contact your doctor to re-evaluate your treatment plan.
Yes, you can typically stop taking fexofenadine suddenly without experiencing physical withdrawal symptoms or 'addiction' issues. Unlike some other classes of medications, antihistamines do not require a gradual tapering off. However, if you are taking the medication to manage chronic conditions like hives or persistent seasonal allergies, your symptoms will likely return once the drug is fully cleared from your system, which usually takes about 2 to 3 days. If you find that your symptoms return with high intensity, it is a sign that the underlying allergy is still present. Talk to your doctor before stopping the medication if you are using it for a long-term condition.
If you miss a dose of fexofenadine, you should take it as soon as you remember. However, if it is almost time for your next scheduled dose, it is better to skip the missed dose entirely and continue with your regular schedule. You should never take two doses at once to 'make up' for a missed one, as this can increase the risk of side effects like headache or dizziness. To help you remember your doses, try taking the medication at the same time every day. If you frequently miss doses, consider using a pill organizer or a smartphone reminder app. Consult your pharmacist if you have specific questions about your dosing schedule.
Weight gain is not a commonly reported side effect of fexofenadine in clinical trials or post-marketing surveillance. While some older antihistamines have been linked to increased appetite and weight gain due to their effects on certain receptors in the brain, fexofenadine is highly selective for peripheral H1 receptors and does not significantly cross the blood-brain barrier. Therefore, it is unlikely to interfere with the metabolic processes or hunger signals that lead to weight changes. If you notice unexpected weight gain while taking this medication, it is more likely related to other factors such as diet, lifestyle, or other underlying health conditions. Discuss any significant weight changes with your healthcare provider.
Fexofenadine can be taken with many other medications, but there are some important exceptions you should know about. You should avoid taking it at the same time as antacids containing aluminum or magnesium, as these can significantly reduce the absorption of the antihistamine. It also has a unique interaction with fruit juices like grapefruit, orange, and apple juice, which can make the drug less effective. While it does not have the same dangerous heart interactions as older antihistamines, it is always vital to provide your doctor or pharmacist with a complete list of all prescriptions, over-the-counter drugs, and herbal supplements you are using. This allows them to check for any specific interactions that might apply to you.
Yes, fexofenadine is widely available as a generic medication and is sold under various brand names, most notably Allegra. Generic versions are required by the FDA to have the same active ingredient, strength, dosage form, and route of administration as the brand-name product. They must also prove 'bioequivalence,' meaning they work in the body in the same way and over the same amount of time. Choosing a generic version can often save you a significant amount of money while providing the same therapeutic benefit for your allergies or hives. You can find generic fexofenadine both as a prescription and over-the-counter at most pharmacies and grocery stores.
Other drugs with the same active ingredient (Fexofenadine)