Allergy Medicines: OTC vs. Prescription

Medically Reviewed by Jennifer Robinson, MD on August 11, 2022
3 min read

With so many over-the-counter (OTC) allergy products in the store, it can be hard to know which one to take. Or do you need a prescription?

Both prescribed and OTC drugs are regulated by the FDA to ensure that they're safe and effective when you follow the directions. But all medications have side effects. Some medications can cause problems when you're taking other medicines, too.

Given all the options and things to consider, it's best to work with your doctor or allergy specialist to figure out whether an OTC or prescription medication is right for you. You'll want to tell them about your symptoms and any medicines you've tried in the past.

You don’t need a prescription to buy OTC medicine. For the medications that you think of as prescription, you do.

Sometimes, the same drug comes in both OTC and prescription versions. The difference is often the strength. For example, hydrocortisone can treat skin reactions including itching and redness. If you're bothered by an insect bite, you can get an OTC cream or spray with a concentration of 1% or less. But for a more severe reaction like eczema, your doctor may prescribe 2.5% hydrocortisone cream or ointment.

In other cases, a prescription medication works in a different way than what you can buy over the counter.

If you have hay fever, you can treat the sneezing and stuffy, itchy nose with an OTC antihistamine such as cetirizine (Zyrtec), fexofenadine (Allegra), or loratadine (Claritin). These block chemicals called histamines, which your body releases when your allergy is triggered. Or your doctor could prescribe a medication like montelukast (Singulair), which blocks a different chemical so your body won't react as much.

Another difference might be how long it takes for you to feel better. Those OTC antihistamines typically start working in about an hour, but it may be a couple of days before the prescription really kicks in.

Most OTC medicines, including antihistamines and nasal steroids, are safe to use as directed for as long as your symptoms last, but there are some exceptions. Don't use a decongestant nasal spray for more than 3 days unless your doctor says to. It could stop working and make your stuffiness worse.

Talk to your doctor about other potential risks. One study found a link between dementia and using high doses of some OTC antihistamines for many years, such as diphenhydramine (Benadryl).

When your allergies could be life-threatening or get in the way of living your life, you should see a specialist, called an allergist.

You may need a prescription if your allergy symptoms are:

  • Several months out of the year
  • Affecting your day-to-day activities
  • Not controlled by OTC medications, or those medicines cause unpleasant side effects

If you're taking a prescription medicine for your allergies, ask your doctor before you also take an OTC medication, especially an antihistamine, for those same symptoms. Using some medicines together can cause more side effects or even set off a dangerous reaction.

Tell your doctor about everything you take: all the pain relievers, remedies, vitamins, and supplements, too.

Your doctor might also write a prescription for an OTC medicine so that it's covered by your health insurance. You'll need to check the rules for your plan -- your copay and your flexible spending account or your health savings account -- to figure out what's going to cost less.

Kids may be able to use the same OTC products as adults, but in smaller doses. Follow the directions on the label. Some OTC medicines are made specifically for children, like antihistamine syrups and chewable tablets.

Call your child's doctor or check with a pharmacist if you have any questions.