Antihistamines: Uses, common brands, and safety info

Over 50 million people in the United States have allergies. There are different types of allergies. Perennial allergies can occur anytime throughout the year or even year-round. Perennial allergies are often related to triggers like mold, dust, or animal dander. Seasonal allergies, also called hay fever (even though they do not cause fever), cause symptoms during certain times of the year, often spring, summer, and fall, due to triggers like grass and pollen. Some people are allergic to certain things, such as a particular medication or food(s), insect bites or stings, or latex. 

Allergy symptoms occur when your body mounts an immune response—your body thinks it is protecting you against a foreign substance. Allergy symptoms can range anywhere from mild to severe or even life-threatening. Symptoms can include a runny or stuffy nose, itchy and watery eyes, sneezing, swelling, skin rashes, and even asthma (with symptoms such as shortness of breath and wheezing). Treatment of allergies can include a variety of approaches, including avoidance of triggers, medications, and allergy shots. 

One common class of medications used to treat allergies is called antihistamines. Antihistamines are available by prescription and over-the-counter (OTC) and are available in a variety of formulations. This article will review information about antihistamines, including uses, names, and safety information.  

Note: Food allergies can also occur and can be serious and life-threatening. Sometimes antihistamines are used as part of a treatment plan to treat mild allergic reactions to food, but people with food allergies should work closely with their allergist/immunologist to develop an action plan. 

The following chart is a list of antihistamines that are currently available. Antihistamines can be found as single-ingredient products or in combination products with other medications. If you are looking at OTC allergy medications, the allergy medication aisle at the pharmacy can be confusing due to the many products available. Your pharmacist can help you select the most appropriate product based on your symptoms, other medical conditions, and other medications you take. 

RELATED: Allergy Season

Other Antihistamines

These antihistamines can be found in single-ingredient or combination products by prescription or OTC.

• Antivert (meclizine)

• Bonine, Dramamine Less Drowsy (meclizine)

• Brompheniramine 

• Carbinoxamine

• Clemastine

• Doxylamine 

• Dramamine (dimenhydrinate)

What are Antihistamines?

An allergy is when your immune system responds to substances that are usually not harmful. People with allergies have an oversensitive immune response. When the immune system recognizes an allergen (a substance that causes an immune response), it releases chemicals such as histamines. Histamines cause allergy symptoms like runny nose, itching, and sneezing. Antihistamines are medicines that provide allergy relief. Antihistamines block the effects of histamine. They are available in many forms, including pills, chewable or dissolving tablets, liquids, creams, eye drops, and nasal sprays. Injectable forms are also available and are primarily used in a healthcare setting such as a hospital or clinic.

How do Antihistamines work?

Histamine triggers the immune system to react and cause symptoms such as itching, sneezing, and runny nose. Antihistamines work by blocking the action of histamine at the H1 receptor (histamine receptor). Blocking the effects of histamine leads to fewer allergy symptoms. 

What are Antihistamines used for?

Depending on the specific medication, antihistamines may be used for:

• Allergic rhinitis

• Allergic conjunctivitis

• Allergic skin reactions

• Sinusitis symptoms (antihistamines will not cure an infection)

• Hives (also called urticaria)

• Angioedema

• Atopic dermatitis

• Bronchitis

• Motion sickness

• Nausea and vomiting

Certain antihistamines may be used off-label for insomnia. For example, Unisom is marketed as a sleep aid, and contains the antihistamine diphenhydramine or doxylamine, depending on the formulation. Other off-label uses of antihistamines include anxiety and motion sickness. 

Types of Antihistamines 

First-generation antihistamines

The U.S. Food and Drug Administration (FDA) approved some antihistamines in the 1930s. These first-generation antihistamines, as they are called, cross the blood-brain barrier and cause drowsiness and other side effects, which can be especially bothersome in older adults and/or when combined with certain other medications. Some examples of first-generation antihistamines include Benadryl, brompheniramine, chlorpheniramine, and hydroxyzine. 

Second and third-generation antihistamines

Second and third-generation antihistamines, which started to appear in the 1980s, do not cross the blood-brain barrier to the same extent as first-generation antihistamines. They cause less drowsiness and other side effects and have fewer drug interactions than first-generation antihistamines. Second and third-generation antihistamines are considered to be safer than first-generation antihistamines. Some examples of these “newer” antihistamines include Claritin, Zyrtec, Allegra, and Xyzal.

Who can take Antihistamines?

Before taking an antihistamine, tell your doctor or pharmacist about all of your medical conditions. Be sure to mention all of the medications you take, including Rx and OTC meds, vitamins, and supplements. This information will help your healthcare provider determine if an antihistamine is safe for you. 

Men 

Men can take antihistamines, provided that they do not fall into one of the restricted categories listed below. 

Women 

Women (who are not pregnant or breastfeeding) can take antihistamines, provided that they do not fall into one of the restricted categories listed below. 

Women who are pregnant or breastfeeding 

Women who are pregnant or breastfeeding should consult their healthcare provider before taking an antihistamine. 

In terms of pregnancy, the Centers for Disease Control and Prevention (CDC) reports that most antihistamines do not cause harm to the unborn baby, but that more research is needed. The CDC recommends consulting the healthcare provider regarding antihistamine use during pregnancy. 

It is preferable to use a less sedating antihistamine such as Claritin, Allegra, or Zyrtec in breastfeeding women. However, the decongestant pseudoephedrine (found in Claritin-D, Allegra-D, and Zyrtec-D), can potentially affect milk supply. Still, it is best to consult the healthcare provider for medical advice before using any new medications while breastfeeding. 

Children 

Children can take antihistamines, depending on the age and medication. For example, Claritin liquid can be used in children aged 2 years and older, but the tablets can only be used in children 6 years and older. Ask your pharmacist or pediatrician for a recommendation that is suitable for your child’s age. 

Older adults

Older adults should avoid first-generation antihistamines, which are more likely to cause side effects such as anxiety, confusion, sedation, blurry vision, reduced alertness, problems urinating, and constipation. The second and third-generation antihistamines are safer for older adults.  

Are Antihistamines safe?

Recalls

No antihistamine recalls found.

Restrictions

People with certain medical conditions should consult their healthcare provider before taking a first-generation antihistamine:

• High blood pressure

• Heart disease

• Lung problems 

• Thyroid disease

• Urinary or prostate problems 

• Glaucoma 

• Pregnancy or breastfeeding

Also, people with kidney or liver problems, or who are pregnant or breastfeeding, should consult their doctor before taking a second-generation antihistamine.

Are Antihistamines controlled substances?

No, antihistamines are not controlled substances.

Common Antihistamines side effects

Antihistamines are generally well tolerated. The most common side effects of antihistamines include:

• Drowsiness (the degree of drowsiness depends on the individual drug, with first-generation antihistamines causing more drowsiness and the newer antihistamines causing less drowsiness)

• Dizziness 

• Dry mouth

• Headache 

• Cough/sore throat 

• Blurry vision

• Appetite loss

• Feeling irritable, nervous, or excited

• Nausea and vomiting

Severe side effects are rare. If you have symptoms of an allergic reaction to an antihistamine, such as hives, difficulty breathing, or swelling around the face, lips, tongue, or throat, get emergency medical care right away.

The above list includes the most common side effects of single-ingredient antihistamines. When an antihistamine is one ingredient in a combination product that contains several ingredients, different side effects are possible, depending on the other ingredient(s) in the product. Other side effects may occur. Consult your healthcare professional for a full list of side effects. 

How much do Antihistamines cost?

With a variety of formulations available, antihistamines are quite affordable. You can purchase a month’s supply of a generic antihistamine over-the-counter for about $10-$20. Brand-name products are more costly, so choosing a generic will always save money. Most antihistamines, in the generic form, are relatively inexpensive. If you have a prescription, using a free SingleCare card can save you even more money. Our customers save up to 80% off the prices of their medications. To use the SingleCare savings on an OTC antihistamine, a prescription is required.