Antihistamines to Treat Eczema

Histamine is a chemical found naturally in all tissues of the body. It helps send messages between cells and plays a key role in allergies.^1,2

The role of histamine in allergies is clear. It is released by mast cells (allergy cells) in response to allergens. When this happens, people experience symptoms like:^1-3

• Watery eyes
• Itching
• Swelling
• Hives
• Sneezing
• Coughing

Taking an antihistamine medicine that blocks or slows this reaction can help relieve allergy symptoms.³

But studies on the benefits of antihistamines for people with atopic dermatitis (eczema) are mixed. Most show no real benefit in reducing symptoms and disease. The main benefit appears to be the fact that some oral antihistamines cause drowsiness (sedation).⁴

When are antihistamines recommended?

Some people with eczema may also live with allergic conditions. Antihistamines may be useful in managing these conditions. They include:⁵

• Hay fever or environmental allergies (allergic rhinitis)
• Food allergies
• Eye allergies (allergic conjunctivitis)

Your doctor may recommend antihistamines to help manage symptoms of these conditions. Be sure to talk to your doctor about whether the recommended antihistamine is sedating or not.⁵

How do antihistamines work?

Histamine is a chemical that has many functions. It affects fluid movement into vessels, dilation of vessel walls, stomach acidity, and brain inflammation. It also stimulates allergic reactions.³

When histamine is released during an allergic reaction, it tries to protect you from something it thinks is harmful. This process causes symptoms like a runny nose, sneezing, and watery eyes. All of these symptoms serve to push out the allergen.³

First-generation antihistamines act on histamine receptors in the body. Some of these drugs may cause drowsiness and fatigue. This happens because the drug crosses the blood-brain barrier. These drugs are called first-generation antihistamines because they were developed in the 1930s.⁶

Second-generation antihistamines were developed in the 1980s. Third-generation antihistamines are even newer. Some doctors consider these drugs safer than the older ones. These also act on histamine receptors in the body but do not generally penetrate the brain. This means these drugs are less likely to cause drowsiness and have fewer side effects.^3,7,8

Examples

There are two types of antihistamines: oral and topical.^9,10

Oral antihistamines

Severe and constant itching can negatively affect a person’s quality of life. When certain oral antihistamines cause sedation, they can temporarily relieve itchiness. They also help by blocking histamines’ ability to stimulate nerves that cause itching.^4,9-11

Oral antihistamines are sometimes recommended for people with eczema if they have allergies as well. Eczema itch is not driven by histamine but rather by an immune chemical called a cytokine.^4,9-12

Examples of oral antihistamines sometimes recommended for people with eczema include:^9,11

• Diphenhydramine (Benadryl^®)
• Hydroxyzine (Atarax^®, Vistaril^®)
• Cyproheptadine (Periactin^®)

Talk to your doctor to see if oral antihistamines are a good treatment option for you.

Topical antihistamines

Topical antihistamines are not recommended to relieve symptoms of eczema. Experts do not think they are useful because histamine is not involved in eczema itch. Topical antihistamines should never be used on broken skin.^9,11

What are the possible side effects?

Side effects can vary depending on the specific antihistamine you are taking. Common side effects of drowsy oral antihistamines include:⁴

• Dry mouth
• Blurred vision
• Increased heart rate
• Drowsiness and sleepiness

Putting topical antihistamines on large or broken areas of skin can cause serious side effects. These include systemic (body-wide) toxicities and toxic psychosis. This is especially a risk in children.¹¹

These are not all the possible side effects of antihistamines. Talk to your doctor about what to expect when taking an antihistamine. You also should call your doctor if you have any changes that concern you when taking an antihistamine.

Other things to know

Medicines that cause sedation, like some antihistamines, should be used with caution. School-age children may have trouble paying attention in class after taking a drowsy antihistamine. Adults may be unable to safely drive or operate machinery after taking one. But if itching is causing poor sleep, taking a drowsy oral antihistamine before bed may help.⁴

Before beginning any new treatment for eczema, tell your doctor about all your health conditions and any other drugs, vitamins, or supplements you take. This includes over-the-counter drugs.