Zyrtec for Hives and Allergic Reactions

Zyrtec (cetirizine) is an over-the-counter antihistamine used to treat hives (urticaria) and seasonal allergies (allergic rhinitis, or hayfever).

Zyrtec is in the class of drugs referred to as second-generation antihistamines. It is recommended for children 2 years of age and older and for adults. It is available as a tablet that can be swallowed, as a chewable tablet, and as a liquid.

This article explains how Zyrtec works for treating hives and seasonal allergies, its potential side effects, and how it compares to other antihistamines.

What Causes Hives and Allergies

An allergic response happens when the immune system responds abnormally to an otherwise harmless substance with antibodies called Immunoglobulin E (IgE). The antibodies act on other cells, including those that release histamine.

Urticaria (hives) appear as part of the allergic response, often due to food or medication allergies. These red, itchy bumps on the skin can form a rash, often associated with angioedema (swelling). Related allergy symptoms can include:

• Runny nose (rhinitis)
• Itchy eyes and watery eyes
• Sneezing
• Sinus pressure or headache
• Skin rashes, red skin, or flaking skin

In some cases, a severe allergic reaction (anaphylaxis) can be life-threatening.

How Zyrtec Relieves Hives and Allergy Symptoms

Zyrtec and other antihistamines work by blocking histamines to reduce symptoms that followed your allergic exposure. These drugs can include antihistamines like Benadryl (diphenhydramine), a first-generation drug with side effects that include drowsiness, or second-generation drugs with milder effects like:

• Zyrtec
• Xyzal (levocetirizine)
• Claritin (loratadine)
• Allegra (fexofenadine)

Zyrtec is approved for the treatment of hives and symptoms of allergic rhinitis. It can be a good choice for allergies and hives, though it can cause sedation and fatigue in some people.

Zyrtec antihistamines include adult and pediatric versions that can be used for allergies to both indoor and outdoor irritants. Zyrtec-D also contains a decongestant, so you should not take it with Sudafed (pseudoephedrine).

Side Effects of Zyrtec

Zyrtec has a low incidence of side effects and is usually well-tolerated. Common side effects include:

• Sedation
• Fatigue
• Dizziness
• Dry mouth
• Sore throat

Some research has also linked regular use of antihistamines like Zyrtec with weight gain.

Who Can Take Zyrtec?

During pregnancy, those with allergic rhinitis or hives may notice a worsening of their symptoms, an improvement, or things may stay the same.

Zyrtec has a pregnancy category "B" rating, meaning that it is generally considered to be safe during pregnancy. In contrast, some allergy medications should usually be avoided during pregnancy including intranasal antihistamines and first-generation antihistamines (such as Benadryl).

With children, it's important to weigh the benefits of treatments (reduction of symptoms) against the possible risks and side effects, such as drowsiness. Your pediatrician can help you find the best antihistamine for your child.

Dosage

The standard dosage of Zyrtec is 2.5 milligrams (mg)—which is equivalent to 1/2 teaspoon—for children 2 to 6 years of age, and 5-10 milligrams for those aged 6 years and older. Larger doses have not been shown to be more beneficial for the treatment of hay fever, but may be more useful for the treatment of hives in some people.

Zyrtec starts to work within an hour or so after taking the medication—making it useful for the as-needed treatment of hay fever and hives. Taking it daily, however, may result in better overall control of allergy symptoms. This is in contrast to some medications, particularly nasal steroid sprays, which need to be taken for some time to be effective.

Warnings and Interactions

People who are diagnosed with a kidney or liver disease should not take Zyrtec without first speaking to a healthcare provider. You also should be cautious about its use with other sedative medications, including alcohol and tranquilizers.

It is possible to have an allergic reaction to Zyrtec itself. The allergy symptoms (hives, wheezing) may be more likely in people who have soy or peanut allergies and take Zyrtec in capsule form. Talk to a healthcare provider about Zyrtec use if you have an allergy to other food additives as well.

Other possibilities are a stomach ache, irritability, headache, and diarrhea (especially in small children). Call your healthcare provider if you experience any of these.

Zyrtec vs. Other Antihistamines

Multiple studies suggest Zyrtec is safe and effective for treating allergies and hives, with fewer side effects when compared to older drugs like Benadryl (diphenhydramine) or Triaminic (chlorpheniramine).

A 2018 study on treating hives found Zyrtec and Allegra (fexofenadine) were among the most effective second-generation antihistamines.

When to See a Healthcare Provider

Generally, it's a good idea to discuss your allergy symptoms with your healthcare provider. They can rule out other health conditions to diagnose an allergy or help with a referral to an allergist.

You also can discuss your treatment options, including other common allergy treatments. If you are not getting symptom relief with over-the-counter medication, you may need a prescription or you may want to consider eye drops, intranasal corticosteroids, or immunotherapies.

Summary

Zyrtec is an over-the-counter antihistamine that is used to relieve hives and symptoms of allergic rhinitis. It is in a class of drugs known as second generation antihistamines. These typically have fewer side effects than first generation antihistamines (such as Benadryl) and are considered preferable in most circumstances.

While Zyrtec is generally considered safe and effective, talk to your healthcare provider before using it. Some people may be at risk of side effects or complications because of other health conditions or medications they take.