Before You Buy Antihistamines

Antihistamines in blister pack
Common Antihistamines. BSIP/UIG / Getty Images

Find out everything you need to know about antihistamines. What symptoms they treat, who should take them and who should not.

Check Your Symptoms

Antihistamines treat:

  • sneezing
  • runny nose
  • watery eyes
  • itchiness
  • scratchy throat

When You Should Take Them

There are prescription and non-prescription antihistamines. They can last anywhere from 4 to 24 hours. Over the counter antihistamines used for occasional cold symptoms usually need to be taken every 4-6 hours.


    You should not take an over the counter antihistamine for more than 7 days before talking to your doctor. If your symptoms last longer than 7 days, you may have developed something more serious.

      Important Things to Tell Your Doctor

      You should tell your doctor if you have any of the following before taking an antihistamine:

      • asthma or chronic bronchitis
      • high blood pressure
      • glaucoma
      • liver disease
      • kidney disease or difficulty urinating
      • prostate problems
      • ulcers or other stomach problems
      • other chronic illnesses
      • pregnant, trying to get pregnant or breastfeeding
      • ALL medications you are taking, including herbal supplements

        Common Antihistamines

        Some common names for antihistamines are:

        • Benadryl - diphenhydramine (generic)
        • Claritin - loratadine (generic)
        • Zyrtec - cetirizine (generic)
        • Allegra - fexofenadine (generic)
        • Triaminic - chlorpheniramine (generic) - for children

        More about Over the Counter Cold and Flu Medications

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