The Allegra Allergy package calls it non-drowsy - but that is not a guarantee for every person: MedlinePlus lists drowsiness and tiredness among the possible side effects of fexofenadine, the active ingredient in Allegra.
The product's Drug Facts Warnings section does not include a drowsiness warning. This page is about Allegra Allergy 12 Hour and 24 Hour tablets (fexofenadine HCl 60 mg and 180 mg); if your box lists different active ingredients, its own Drug Facts label is the one that applies.
What the label says
Allegra Allergy tablets have one active ingredient - fexofenadine HCl (60 mg in the 12 Hour tablet, 180 mg in the 24 Hour tablet), an antihistamine. The drowsiness question is answered by two sources: MedlinePlus's fexofenadine side-effect list and the product's own label:
Who should ask a doctor first
The Allegra Allergy label says do not use it if you have ever had an allergic reaction to this product or any of its ingredients.
The label says to ask a doctor before use if you have kidney disease - your doctor should determine if you need a different dose - and its directions say adults 65 years of age and older should ask a doctor before use, and children under 12 should not use these tablets.
If you are pregnant or breastfeeding, the label says to ask a health professional before use, and MedlinePlus says to call your doctor if you become pregnant while taking fexofenadine. A pharmacist or your prescriber is the right reviewer for your full medication list. An AI consult can help you work out what to ask; it is not a substitute for that review.
Common questions
Does Allegra make you drowsy?
It can: MedlinePlus lists drowsiness and tiredness among the possible side effects of fexofenadine, Allegra's active ingredient. The product's Drug Facts Warnings section does not include a drowsiness warning - an absence that is not a promise either way.
Is Allegra non-drowsy?
The package calls it non-drowsy, and its Drug Facts Warnings section carries no drowsiness warning. MedlinePlus still lists drowsiness and tiredness as possible fexofenadine side effects - so the claim is not a guarantee for every person.
Can Allegra keep you awake?
Neither source checked for this page - the Allegra Allergy label and MedlinePlus's fexofenadine page - lists sleeplessness among its warnings or possible side effects. That absence does not prove it cannot happen; if you notice unexpected or persistent sleep changes while taking it, ask a pharmacist or your doctor.
What should I avoid taking with Allegra?
The label says do not take it at the same time as aluminum or magnesium antacids, and do not take it with fruit juices. MedlinePlus names orange, grapefruit, and apple juice, and says to take an aluminum or magnesium antacid a few hours before or after fexofenadine.
Does this apply to every Allegra product?
This page covers Allegra Allergy 12 Hour and 24 Hour tablets (fexofenadine HCl) only. Check the Drug Facts on your own box - the active ingredients listed there are the label that applies to it.