Allergists’ Group Recommends Newer Antihistamines Over Older Antihistamines for Nasal Allergies and Hives

Allergic rhinitis or hay fever (inflammation of the upper respiratory tract caused by an allergen such as tree or grass pollen, pet hair or dust resulting in itching of the nose or throat, runny nose, sneezing and watery eyes)[1] and urticaria or hives (skin inflammation caused by a drug, food or other allergen resulting in a rash with red welts and itching)[2] are characterized by the release of histamine, which causes these allergic symptoms.

The most effective way to manage allergic rhinitis and urticaria is to discover the causative allergens and to avoid them. If that is not possible, oral antihistamines (medications that block histamine) are the most common drugs used to relieve the symptoms of these conditions.

Oral antihistamines are divided into older (first-generation) and newer (second- and third-generation) agents. Because of the better safety profile of newer antihistamines, Public Citizen’s Health Research Group has previously recommended their use over older antihistamines for both allergic rhinitis and urticaria.[3],[4] A recent position statement by the Canadian Society of Allergy and Clinical Immunology (CSACI) that summarized the research evidence about these drugs reinforces our recommendation.[5] The statement was published online on Oct. 1, 2019, in Allergy, Asthma and Clinical Immunology.

Types of oral antihistamines

Older oral antihistamines, such as the common over-the-counter and prescription drug diphenhydramine (BENADRYL), have been used for the treatment of allergic conditions for over 70 years. Because these drugs were approved before the current drug-approval standards were implemented, they did not undergo rigorous effectiveness and safety reviews by the Food and Drug Administration. However, newer oral antihistamines (see Table, below, for examples), which were introduced since the 1980s, have been studied extensively before they were approved and are considered a better alternative to older antihistamines.

Examples of Commonly Used Oral Antihistamines for Nasal Allergies and Hives by Type†

†Combination drugs were excluded from this table.
*Do Not Use to treat allergic rhinitis or urticaria
**Available in both prescription and over-the-counter formulations

More benefits for newer antihistamines

In its summary of the effects of antihistamines, the CSACI position statement indicates that newer agents reach their maximum concentration in the blood faster, which makes them more effective for relieving allergy symptoms, than older agents.

For example, studies show that it takes 50 minutes for the newer agent cetirizine (CHILDREN’S ZYRTEC ALLERGY, CHILDREN’S ZYRTEC HIVES RELIEF, ZYRTEC ALLERGY) to reduce allergic flare symptoms by one-half, whereas it takes 79 minutes for the older agent diphenhydramine to reduce these symptoms by the same amount. In addition, the effects of newer agents last just as long or longer than those of older antihistamines.

Fewer risks with newer antihistamines

Older antihistamines pass more easily from the bloodstream to the brain, which can suppress the central nervous system, resulting in adverse effects that range from drowsiness to significant sedation, respiratory depression, coma or death. These effects also can cause traffic or aviation accidents as well as injuries from operating machinery. Therefore, older antihistamines are banned for use by airline pilots before or during flights. These older antihistamines should be avoided in young children because they can cause agitation and may be dangerous in infants.[6] In addition, these drugs have been linked to decreased school performance.[7]

In contrast, newer antihistamines have a decreased ability to cross the blood-brain barrier and have minimal serious risks. According to the CSACI position statement, there have been no deaths due to these drugs in Canada. Furthermore, the newer agents fexofenadine (ALLEGRA, CHILDREN’S ALLEGRA) and loratadine (ALAVERT, CLARITIN and others) are permitted in Canada for use by truck drivers and others who perform complex tasks like operating heavy machinery.

Additionally, older antihistamines have more anticholinergic adverse effects (including dry mouth, constipation, double vision, blurred vision, urinary retention and increased heart rate) than newer antihistamines. These adverse effects are especially problematic in older adults, particularly those with an enlarged prostate, which makes men more susceptible to urinary retention, or those with glaucoma (high pressure in the eyes).

Finally, another advantage of newer agents is that they have fewer interactions with other drugs than do older antihistamines.

What You Can Do

If you have allergic rhinitis or urticaria, talk to your primary care doctor first about treatment options. For severe allergies, your doctor may refer you to an allergy specialist. If your doctor recommends an oral antihistamine, opt for a newer-generation agent. Do not use older antihistamines for these conditions. Do not use any antihistamine to treat colds because they are not approved for such uses. In case of anaphylaxis (severe allergic reactions characterized by sudden troubled breathing and widespread hives), seek immediate medical help and use an epinephrine (ADRENACLICK, AUVI-Q, EPIPEN, SYMJEPI) injection instead of antihistamines.

Report all serious adverse events related to prescription and over-the-counter antihistamines to the FDA’s MedWatch adverse event reporting program by visiting http://www.fda.gov/MedWatch or by calling 800-FDA-1088.
 

References

[1] deShazo RD, Kemp SF. Pharmacotherapy of allergic rhinitis. UpToDate. April 10, 2020.

[2] Asero R. New-onset urticaria. UpToDate. April 2, 2020.

[3] Treatment for nasal allergies: An updated review. Worst Pills, Best Pills News. April 2016. /newsletters/view/1027. Accessed May 27, 2020.

[4] Another look at first-generation antihistamines. Worst Pills, Best Pills News. May 2016. /newsletters/view/1034. Accessed May 27, 2020.

[5] Fein MN, Fischer DA, O’Keefe AW, Sussman GL. CSACI position statement: Newer generation H1-antihistamines are safer than first-generation H1-antihistamines and should be the first-line antihistamines for the treatment of allergic rhinitis and urticaria. Allergy Asthma Clin Immunol. 2019;15(October 1):61.

[6] deShazo RD, Kemp SF. Pharmacotherapy of allergic rhinitis. UpToDate. April 10, 2020.

[7] Walker S, Khan-Wasti S, Fletcher M, et al. Seasonal allergic rhinitis is associated with a detrimental effect on examination performance in United Kingdom teenagers: Case-control study. J Allergy Clin Immunol. 2007;120(2):381-387.