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Is it safe to take an antihistamine every day?

If springtime flowers bring sniffling, sneezing, and itching, you’re not alone. Allergies are one of the most common chronic conditions worldwide, affecting up to 50 million Americans, according to the American College of Allergy, Asthma, and Immunology. If you’ve ever faced those pesky symptoms, chances are you’ve taken an antihistamine for relief. 

What are antihistamines?

Antihistamines are a class of drugs used to control the body’s production of histamine, a chemical made by your immune system in response to common allergens like mold, dust, pollen, ragweed, pets, insect bites/stings, latex, and food. The release of too much histamine spurs bothersome symptoms like itchy eyes, coughing, sneezing, runny nose, congestion, itchy throat, itchy skin, rashes, wheezing, shortness of breath, nausea, vomiting, insomnia, and fatigue.

Antihistamines are classified into two groups: 

  1. First-generation antihistamines work in the part of the brain that causes motion sickness. Meaning, they can help with nausea and vomiting, too. Their most common side effect is severe drowsiness. Benadryl, Unisom, and Vistaril are some popular brand names in this category. 
  2. Second-generation antihistamines are newer medications with fewer side effects. They don’t typically cause drowsiness. Because they are less sedating and don’t interact with as many drugs as their first-generation counterparts, research says second-generation antihistamines are safer; they’re also more effective. Allegra, Claritin, and Zyrtec are some common brand names in this group.

Seasonal allergies are typically limited to the spring, summer, and early fall, but perennial allergies can occur year-round. If it’s not possible to eliminate exposure to your allergy trigger, you may keep daily symptoms under control with an antihistamine.

Is it safe to take an antihistamine daily?  

Experts say, it’s usually okay. “Taken in the recommended doses, antihistamines can be taken daily, but patients should make sure they do not interact with their other medications,” says Sandra Lin, MD, professor and vice director of Otolaryngology-Head & Neck Surgery at John Hopkins School of Medicine. 

In other words, you’ll need to make sure that you choose the right antihistamine for everyday use. First-generation antihistamines come with risk of more side effects and interactions, so are not generally advised for long-term usage. Additionally, frequent use of the first generation antihistamines may lead to excessive weight gain. 

“With first-generation antihistamines, some people note decreasing effectiveness if used daily for several days,” says Dr. Lin. Because they cause drowsiness, they are not safe to mix with alcohol—something to consider if you plan to have a drink during allergy season.

RELATED: Is it safe to drink alcohol while taking allergy medicine?

The risk of interaction increases with combination products. Some allergy medications contain an antihistamine and a decongestant (e.g., Claritin D). “The decongestant component can cause elevated blood pressure and elevated heart rate,” says Stephen Tilles, MD, clinical professor of medicine at the University of Washington. However, Dr. Lin says antihistamines alone are “not bad for the heart in otherwise healthy people.”

“The later generation non-sedating antihistamines, such as loratadine, fexofenadine, and cetirizine are safe to take daily,” says John Faraci, MD, assistant professor at Loma Linda University School of Medicine. “In some people, cetirizine may cause people to feel sleepy or drowsy, but it’s unlikely.” Second-generation antihistamines maintain their effectiveness when you take them every day.

Use this table as a quick reference guide for which medications are safe, but always consult with your pharmacist or healthcare provider before adding a medication to your daily regimen. 

Safety and dosage guidelines for daily use of antihistamines
Drug name Generation Recommended dosage Safe to take daily? Get coupon
Aller-Chlor (chlorpheniramine) First 4 mg every 4-6 hours No Get coupon
Benadryl (diphenhydramine) First 25mg to 50 mg every 4-6 hours No Get coupon
Dimetapp (brompheniramine maleate) First 4 mg to 8 mg every 6 hours No Get coupon
Periactin (cyproheptadine) First 4mg to 20 mg per day No Get coupon
Ryclora (dexchlorpheniramine maleate) First 2 mg every 4-6 hours No Get coupon
Tavist (clemastine) First 1.34 mg every 12 hours No Get coupon
Unisom (doxylamine) First 50 mg every 4-6 hours No Get coupon
Vistaril (hydroxyzine hcl) First 50mg to 100 mg daily in divided doses Yes Get coupon
Allegra (fexofenadine hcl) Second 60 mg orally twice per day or 180 mg orally once per day Yes Get coupon
Clarinex (desloratadine) Second 5 mg per day Yes Get coupon
Claritin (loratadine) Second 1 tablet orally every 24 hours Yes Get coupon
Zyrtec (cetirizine hcl) Second 5 mg to 10 mg daily  Yes Get coupon

 

Are there side effects from taking antihistamines daily? 

First-generation antihistamines can cause side effects such as:

  • Drowsiness
  • Constipation
  • Urinary retention
  • Dry mouth
  • Increased appetite
  • Weight gain
  • Worsen glaucoma
  • Rapid heart rate

Second-generation antihistamines do not have these side effects, but can cause:

  • Tiredness
  • Headache
  • Cough
  • Sore throat
  • Nausea or vomiting

Rarely, second-generation antihistamines can cause acute liver problems, according to Dr. Lin. While antihistamines “suppress the allergic part of the immune system, no human studies have demonstrated the immune system would be weakened and more likely to have infections [when taking antihistamines],” Dr. Lin explains.

RELATED: Non-drowsy Benadryl—What are your options?

What happens if I stop taking antihistamines daily?

Side effects are rare if you abruptly discontinue antihistamines after regular use. “There are typically no rebound symptoms—it is important to keep in mind that if the antihistamine is working well and is withdrawn, there will be a recurrence of the symptoms the antihistamine was treating,” Dr. Tilles says.

If you do experience side effects after ending a daily antihistamine, they will be mild. “Some people who use antihistamines regularly and then stop suddenly may have side effects of itchy skin and disrupted sleep,” Dr. Lin says. 

What other treatments can I try for allergies? 

If you are concerned about side effects or drug interactions, there are alternative treatments.

Allergy sprays can be an effective treatment option. Nasal corticosteroids are safe for daily use, and don’t cause systemic side effects or interactions that daily pills can.

Certain supplements may alleviate symptoms. Research suggests quercetin, a bioflavonoid derived from plant sources, helps inhibit histamine release. “[Quercetin] works best when started 2-3 weeks prior to allergy season. Continue to take it throughout the season,” says Julia Scalise, Ph.D., a holistic health practitioner and naturologist. Vitamin C, bromelain, butterbur, and apple cider vinegar may also help to boost your immune system so it can better respond to allergens.

Lifestyle changes such as reducing your exposure to allergy triggers or using a HEPA air filter can help to reduce your reaction during peak allergy season.