Your Question: I have allergic asthma and take claritin because it does help. However, on some nights I wake up and the allergies as so bad that nothing seems to do anything. I was wondering if a double dose of claritin would benefit me on those days?
My answer; For the record, the standard dose of Claritin (loratadine) is 10 mg, and you're talking about doubling that dose to 20 mg. Since I am not an expert on allergic medicine, I am going to allow the physicians over at healthtap.com answer your question.
1. Dr. Luis A. Matos: It may make you drowsy. The full adult dose of Loratadine in other parts of the world is 20 mg. This amount caused a 12-14% drowsiness rate. The 10 mg dose was tested in the us in order to find a non-drowsy dose and it worked. If your allergy symptoms are controlled with Diphenhydramine (benadryl-50% drowsiness) and not 10 mg loratadine, you can try a second 10 mg dose and it may help with a lot less drowsiness.
2. Dr. James W. Ferguson: Studies of loritadine show the medication is well tolerated at twice the recommended 10 mg dose. However, the same studies show no added benefit of the double dose in symptom relief over the regular dose schedule.
Concusion: So it appears that it is safe to try a second of Claritin if you want, although it's important to understand there is no evidence it will do any good, and that there will be a slight increase in your risk for side effects, of which the main one is somnolence.