my son has been on allegra d for years he now seems to have side effects when he takes it what amount of time should you be on this med ?
Your son should take the drug as directed by his physician. There is no specific time limit on taking Allegra D.
If he is having reactions to the drug, or if it seems to be ineffective, then he made need to change to another drug. If it's been prescribed or recommended by his doctor, he should not stop taking it until he has talked to his doctor and gotten another prescription or recommendation (if necessary).