All antihistamine medications also has anticholinergic effects, which can contribute to dizziness, sedation, urinary retention, diarrhea, muscle cramp, gastrointestinal discomfort, menstrual cramp which are related to the anticholinergic effects of the medication. Read more Allegra (fexofenadine) is an otc non-sedating antihistamine and as such down regulates the release of histamine from mast cells in the tissue or decreases the effect of histamine that is released.
I do not think it would significantly suppress the immune system which is primarily lymphocyte function. The only thing, you can not do is get skin testing for allergies while on this drug. Read more There is considerable debate about the accuracy of label expiration dates. Read more If you take 1/2 of an Allegra 180 mg you get 90 mg.
Also, during the clinical studies prior to the release of allegra, (fexofenadine) doses of up to 540mg were used without ill effects. Read more But this would make side effects more likely — dry mouth and eyes for example, perhaps sedation / tiredness. Read more Typically, when a medication expires, it's because it loses its potency or effectiveness.
Might think of mixing medicines from different classes if bad allergies are the issue. There are some medications that, with time, do breakdown with time into harmful substances. I would not recommend taking any expired medication. Read more Oral antihistamines like Allegra (fexofenadine) need to be absorbed by the digestive system and distributed thru the body before they are effective--about 20-30 minutes.
One would expect Allegra to take effect in about 2 hrs.
If the reason for switch is due to drowsiness, then you may up the dose of Allegra to 2 to 4 x daily.
It might be worth trying Zyrtec to see if there is any difference in your anxiety.
Talk to your doctor about it and see what is the best option.If you feel allergies are ""severe", you need to visit an allergist for more preventative care. Read more Allegra (fexofenadine) d is a combination of non drowsy antihistamine and pseudo Ephedrine (sudafed).For many people decongestant portion causes jitteriness.Still, the tea may be safe, but the fda has determined the have indeterminate safety. Read more Allegra, Zyrtec and Claritan are all very similar meds and there isn't really one that is better, although one may work better in a certain patient.Benadryl (diphenhydramine) works very differently but has many more side effects than the others, including sedation and need for repeated dosing of the medicine daily.Allegra and xyzal are two different types of antihistamines.