Safety considerations when antihistamines are used

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Many depend on antihistamines to manage allergy symptoms including congestion, runny nose, hives and itchy eyes. These medications are also used to manage nausea, motion sickness, anxiety and dizziness. It is important to note that these drugs include over-the-counter varieties such as loratidine and diphenhydramine and prescription varieties. Even though antihistamines are commonly used and generally safe, they have certain side effects that can cause health issues. Take note that there are even instances where they should not be used at all. If you want to learn more about these medications and how to properly manage the potential side effects that might manifest, read here.

How antihistamines work

The immune system releases histamine as part of the bodily response to infection or physical damage. Being exposed to harmless particles or substances such as pet dander or pollen can trigger the release of histamine. Individuals who are highly sensitive have an immune system that overly reacts to these seemingly harmless substances. The histamine produces localized inflammation which results to itchiness, swelling, sneezing and congestion. Antihistamines work on the central nervous system in order to prevent the release of the histamine by stopping the symptoms but do not completely treat the allergies.

Antihistamines can lead to drowsiness and diminished concentration.

What are the side effects?

Antihistamines can lead to drowsiness and diminished concentration. Take note that this minor side effect can be dangerous if the individual is driving or operating heavy machinery. Using antihistamines is often linked with increased risk of accidents among professional truckers. Drinking alcohol while taking antihistamines will only worsen drowsiness. Remember that the drug can also cause irritability, dizziness and dry mouth. In some individuals, they can also cause hyperactivity and nervousness.


Since antihistamines affect the central nervous system, they can cause reactions all over the body and some can be life-threatening. The use of antihistamines can worsen the symptoms of glaucoma. In some circumstances, those who have emphysema or other conditions that involve breathing problems must not use antihistamines since it will only worsen the breathing.

Among men, the drug makes urinating difficult especially those who have an enlarged prostate gland. Women who are breastfeeding or pregnant must consult a doctor first before using antihistamines. Additionally, antihistamines can worsen memory issues among the elderly who have dementia. The drug can also interact with certain antidepressants and antibiotics and must not be taken with alcohol.

What are the two generations of antihistamines?

It is important to note that second-generation antihistamines which include cetirizine, loratidine and fexofenadine have minimal side effects. These antihistamines do not cross the blood-brain barrier, thus they are less likely to cause hyperactivity or drowsiness.  As for the first-generation antihistamines which include diphenhydramine, cyproheptadine and chlorpheniramine, they can cause the usual side effects but an overdose in children can be deadly. A doctor must be consulted before antihistamines are given to children.

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