Fexofenadine 180 mg is an antihistamine used to treat seasonal allergies. It’s the highest available strength, designed to be taken once a day to relieve sneezing, runny nose, itchy or watery eyes, and itching of the nose or throat. It’s also used to treat chronic hives (urticaria), reducing itching and the number of raised, red welts on the skin.
Sold under the brand name Allegra and available over the counter, fexofenadine belongs to the second generation of antihistamines, meaning it was designed to block your body’s histamine response without making you drowsy the way older allergy medications do.
Seasonal Allergies and Chronic Hives
The 180 mg tablet covers the same two conditions that lower-strength fexofenadine treats, but in a single daily dose rather than two. For seasonal allergic rhinitis (hay fever), it targets the full range of nasal and eye symptoms triggered by pollen, dust mites, pet dander, and mold. For chronic hives that last six weeks or longer without a clear cause, it helps control the itching and rash cycle that can disrupt sleep and daily life.
Fexofenadine works by blocking histamine receptors on cells throughout your body. When you encounter an allergen, your immune system releases histamine, which triggers inflammation, swelling, and itching. Fexofenadine doesn’t stop histamine from being released, but it prevents it from binding to cells and causing symptoms.
Who Can Take the 180 mg Dose
The 180 mg strength is approved for adults and children 12 years of age and older. Younger children use lower doses in different forms, such as oral suspension or smaller tablets.
If you have kidney problems, fexofenadine clears from your body more slowly, which can intensify its effects. The FDA label recommends a lower starting dose for people with reduced kidney function. Older adults are more likely to have age-related kidney changes, so dose adjustments may also apply in that group.
Less Drowsiness Than Other Antihistamines
One of the main reasons people choose fexofenadine is that it causes very little sedation. A review published by the American Academy of Family Physicians compared drowsiness reports across several second-generation antihistamines and found that sedation was least common with fexofenadine. Compared to loratadine (Claritin), fexofenadine had a lower odds of causing drowsiness, with an odds ratio of 0.63. Cetirizine (Zyrtec), by contrast, was roughly 3.5 times more likely to cause sedation than loratadine.
This makes fexofenadine a particularly good fit if you need to stay alert for work, driving, or operating machinery. While no antihistamine is guaranteed to be completely free of sedation for every person, fexofenadine consistently performs best in this category.
How to Take It
Take the 180 mg tablet before a meal with a full glass of water. Timing it before eating helps with absorption. Once a day is all that’s needed at this strength, so most people pick a consistent time, often in the morning, and stick with it.
The most important thing to avoid is fruit juice. Grapefruit, orange, and apple juice all interfere with proteins called drug transporters that help move fexofenadine into your bloodstream. When these transporters are blocked, less of the medication gets absorbed and it may not work as well. The FDA specifically warns against taking fexofenadine with any of these juices. Water is the best choice. If you drink juice regularly, just separate it from your dose by a couple of hours.
Common Side Effects
Fexofenadine is well tolerated overall. In clinical trials, the most frequently reported side effects at the recommended dose were headache, back pain, and mild nausea. These occurred at rates close to what was seen in people taking a placebo, meaning they may not have been caused by the drug at all.
Unlike first-generation antihistamines such as diphenhydramine (Benadryl), fexofenadine does not typically cause dry mouth, blurred vision, or urinary retention. It also does not cross into the brain in significant amounts, which is why drowsiness rates are so low. Serious side effects are rare, but any unusual reaction warrants attention.
What Fexofenadine Does Not Treat
Fexofenadine relieves symptoms but does not treat the underlying allergy itself. It won’t help with nasal congestion on its own, since stuffiness is driven more by blood vessel swelling than by histamine alone. Some combination products pair fexofenadine with a decongestant for that reason. It also is not intended for sudden, severe allergic reactions like anaphylaxis, which require emergency treatment with epinephrine.
For people with mild or occasional symptoms, a lower dose (60 mg twice daily) may be sufficient. The 180 mg once-daily tablet is designed for convenience and steady symptom control throughout the day, making it the most popular choice for daily allergy management during peak pollen seasons or ongoing hive flare-ups.