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More information about Antihistamines

Allergy season can bring many bothersome symptoms for some people, including sneezing, sniffling and watery eyes. While these symptoms might seem like a minor annoyance, they can impact your entire day. Luckily, you may be able to improve your symptoms with over-the-counter allergy medications, such as antihistamines. Walgreens offers many different forms of allergy symptom relief online and in store. If you’re not sure what you’re looking for, ask a Walgreens pharmacist for help.

What are antihistamines?

Antihistamines are a class of medications that block the effect of histamine, a naturally occurring chemical that’s released by your body when you encounter an allergen. Histamine causes symptoms when the body has an allergic response. These symptoms include sneezing, runny nose, itchy eyes and swelling.

How do antihistamines work?

Antihistamines work in different ways, depending on the class of medication. They may work by blocking certain histamine receptors in your body.

Are there different types of antihistamines available?

Yes, there are two different types or classes of over-the-counter antihistamines: first-generation and second-generation antihistamines.

First-generation antihistamines may contain ingredients, such as diphenhydramine, doxylamine, brompheniramine or dimenhydrinate, which can cause drowsiness. Some first-generation antihistamines are sometimes used short term to help with insomnia. These medications may also help prevent motion sickness.

With ingredients like cetirizine, loratadine and fexofenadine, second-generation antihistamines may help relieve allergy symptoms without causing drowsiness. Each medication may work for different amounts of time. Some medications work for four to six hours, while others work for 12 or 24 hours. You can find these medications in different forms, including pills, liquids, eye drops and nasal sprays.

You should pay attention to which antihistamine medications may interact with any other medications you may be currently taking. People with certain medical conditions, such as hypertension or glaucoma, should check with their healthcare provider before taking an antihistamine.

Can antihistamines be used to treat allergies and cold symptoms?

Yes, most antihistamines are intended for relief of allergy or cold symptoms, including sneezing, runny nose, and itchy eyes or throat.

Are there any potential side effects of antihistamine use?

Antihistamines may have side effects, which may be mild or more severe, depending on the individual. Some possible side effects of some antihistamines may include:

  • Dizzines
  • Drowsiness
  • Dry mouth
  • Blurry vision
  • Decreased appetite
  • Nervousness, irritability or feeling jittery

Because you may experience drowsiness or sleepiness from some antihistamines, you should not drive or perform any other coordinated tasks. Do not drink alcohol if you are taking an antihistamine.

How long does it take for antihistamines to take effect?

Depending on the route of administration, antihistamines start working within minutes to hours. Topical applications, such as eye drops or nasal sprays, may act quickly because they are applied to the affected area. However, oral tablets may take between 30 minutes to a few hours to begin working because they must be broken down and absorbed first.

Walgreens offers many different forms and types of antihistamines in store and online. Antihistamines may be taken for relief of symptoms associated with allergies as well as motion sickness. You should consult with your healthcare provider or pharmacist before taking these medications, as they can interact with other medications or make other health conditions worse. Ask your Walgreens pharmacist if an antihistamine may be appropriate for you.

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