A lot of medications are used for treating allergies. Allergy shots or steroids are used for this purpose but antihistamine is the first thing that is usually tried out. Antihistamines are drugs or compounds that prevent the physiological outcomes of histamines, especially for treating allergies and inflammatory reactions.

How Do Antihistamines Help In Treating Allergies?

When the body gets into contact with allergens, chemicals called histamines are produced. The tissue in the nose becomes swollen, nose and eyes become runny, and the nose, eyes, and mouth become itchy. An itchy rash called hives may also appear on the skin. Reducing and blocking histamines, antihistamines prevent allergy symptoms. These medications are truly effective in relieving the symptoms of different types of allergies. However, all the symptoms cannot be relieved. For treating nasal congestion, a decongestant may be recommended by the doctor. Some of the medicines use a combination of an antihistamine and decongestant.

Types of Antihistamines: Prescription-Only & Over-The-Counter

Antihistamines are available in different forms such as tablets, liquids, nasal sprays, capsules, and eye drops. Some are prescription-only drugs and some can be bought over the counter (OTC) at a local pharmacy store.

Some of the prescription-only antihistamines include:

  • Azelastine eye drops (Optivar)

  • Hydroxyzine (Atarax, Vistaril)

  • Carbinoxamine (Palgic)

  • Levocabastine oral (Xyzal)

  • Desloratadine (Clarinex)

  • Azelastine nasal sprays (Astelin, Astepro)

  • Emedastine eye drops (Emadine)

  • Cyproheptadine

  • Levocabastine eye drops (Livostin)

Some of the over-the-counter (OTC) antihistamines include:


  • Clemastine (Tavist)

  • Loratadine (Alavert, Claritin)

  • Brompheniramine (Dimetane)

  • Chlorpheniramine (Chlor-Trimeton)

  • Diphenhydramine (Benadryl)

  • Fexofenadine (Allegra)

  • Cetirizine (Zyrtec)

The eye drops prove effective in the treatment of eye allergy symptoms. Some of the medications relieve congestion by a combination of an antihistamine and a decongestant.

Various Side Effects of Antihistamines

The older histamines cause more side effects, especially drowsiness. Newer antihistamines have not many side effects, so they could be better for some people.

Some of the prominent side effects of antihistamines include:

  • Restlessness or moodiness (in some children)

  • Drowsiness

  • Blurred vision

  • Dizziness

  • Dry mouth

  • Nausea and vomiting

  • Difficulty in peeing or unable to pee

  • Feeling confused

If you’re taking an antihistamine that leads to drowsiness, take it before bedtime. Do not take it in the daytime especially before driving or using machinery.

Always consider reading the label before you consume an allergy drug. Antihistamines may come in contact with other medications that you might be taking.

Moreover, consult your doctor first if you have an enlarged prostate, heart disease, high blood pressure, thyroid problems, kidney or liver disease, a bladder obstruction, or glaucoma. In case of pregnancy or nursing also, consult with a doctor.
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