I Accidentally Took Two Doses Of Allegra

Thanks for reaching out to us! I can certainly understand being worried after accidentally taking two doses of any medication, but, in this case, there isn't too much of a risk here.

Allegra (fexofenadine) is a second-generation antihistamine (similar to Claritin and Zyrtec), a drug class that is, overall, very well-tolerated. You did take over the recommended maximum daily dose (which is 180mg per day), but the risk of severe side effects is low. You may experience some mild side effects, such as:

• Excess sedation
• Dizziness
• Fogginess
• Headache
• Dry mouth

These are the side effects typically associated with Allegra, even at recommended doses.

What Is The Risk Of Serious Side Effects?

Again, it is unlikely you will experience any serious side effects by taking one extra dose of Allegra within 24 hours.

In fact, even though 180mg is the maximum dose recommended by the FDA per day, several studies have tested the drug in individuals at higher dosages and it was well-tolerated.

One study, which tested doses up to 360mg per day (what you took) concluded it was virtually free of side effects. Several others, testing doses up to 240mg, again, find the drug to be very well tolerated.

What Is A Toxic Dose Of Allegra?

Clinical studies show that it takes extremely high doses of Allegra to cause toxicity.

No clinical signs of toxicity or fatalities have been reported in mice and rats receiving oral fexofenadine hydrochloride doses up to 5 g/kg (over 100 times the maximum recommended daily oral dosage in adults).

The prescribing information for Allegra notes that individuals taking doses as high as 690mg twice daily (that's over 7 tablets daily) for one month did not develop significant side effects:

Single doses of fexofenadine hydrochloride up to 800 mg (six normal volunteers at this dose level), and doses up to 690 mg twice daily for 1 month (three normal volunteers at this dose level) or 240 mg once daily for 1 year (234 normal volunteers at this dose level) were administered without the development of clinically significant adverse events as compared to placebo.

Final Words

I hope this answer helped. Overall, taking two doses of Allegra (fexofenadine) should not result in any significant side effects. The drug is well-tolerated and has a wide window for safety.

Having said all of the above, if you feel you have overdosed on any medication or you are feeling concerning symptoms, be sure to contact Poison Control at 1-800-222-1222 or visit Poison.org.

Thanks again!