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Safe Use of Antihistamines

Are you are one of the 50 million people in the U.S. with allergies? Do you suffer with coughing, sneezing, itchy and watery eyes, a runny nose, and a scratchy throat? If so, you may take antihistamines to treat your symptoms. 

Allergens are things you’re allergic to. Examples include pollen, dust, pet dander, even foods or drugs. When an allergen enters your body, your body releases histamine. Histamine causes the familiar symptoms of allergies. Antihistamines relieve symptoms by blocking histamine.  

A lot of different antihistamines are available. They fill the counters and prescription shelves at your local drug store. New ones seem to appear all the time. Antihistamines are found in many different forms for children and adults: liquids, tablets, creams, nasal sprays, and eye drops.  

There are two classes of antihistamines. They work in different ways and have different side effects.

  • The older first-generation antihistamines are also called sedating antihistamines. They cause much more drowsiness and fatigue than the newer antihistamines. (In fact, these antihistamines sometimes are used as sleeping pills.) Side effects can include dizziness, poor coordination, dry mouth, nausea and vomiting, blurred vision, and trouble urinating. One antihistamine in this group is diphenhydramine (Benadryl®). Others are brompheniramine (Bromfed®, Dimetapp®), hydroxyzine (Vistaril®, Atarax®) and meclizine (Antivert®). 

  • The newer second and third-generation or non-sedating antihistamines are used much more frequently. Usually, they don’t cause drowsiness. Antihistamines in this group include cetirizine (Zyrtec®), loratadine (Claritin®), and fexofenadine (Allegra®). In high doses, these antihistamines can still cause drowsiness and rapid heart rate.

Some antihistamines may work better than others for your symptoms. It can be hard to find the one that works just right. If you are desperate (and still coughing and sneezing and itching), you may be tempted to take too much. BUT – it can be dangerous to take extra antihistamines. More is not better.

  • Do NOT “double-up” on a dose.

  • Do NOT take a dose sooner than you’re supposed to.

  • Do NOT take two different antihistamines at the same time.

  • Instead, talk to your doctor or pharmacist if you have trouble finding a drug that works well for your allergy symptoms.

Antihistamines are safe when used as directed. Otherwise, there can be problems:

  • Taking too much can be harmful for children and adults.

  • Some people abuse the sedating antihistamines. They can cause seizures and hallucinations.

  • Some antihistamines are combined with pain medicine. Taking another pain medicine at the same time could cause an overdose.

  • Some antihistamines are combined with decongestants. Taking another decongestant at the same time could cause an overdose.

Follow these guidelines when using antihistamines.

  • Read labels carefully.

    • Some antihistamines should not be used for children.

    • Some antihistamines can interact with other medicines. Check with your doctor or pharmacist if you have questions.

    • Different products may contain the same ingredients. Taking them at the same time can be dangerous.

  • Take (or give) the right dose.

  • Lock antihistamines up high, where children can’t reach them. Children can drink liquid antihistamines, swallow too many pills, or even eat antihistamine creams. Severe poisoning can occur this way.

Not sure which antihistamine is best for you? For your child? Call your doctor or pediatrician. If you took too much, or gave too much to your child, call the Poison Center right away. The 24-hour number is 1-800-222-1222. Specialists in poison information will tell you exactly what to do. 

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June 2012, The Poison Post®