Antihistamines for Itching: What to Know

If you are suffering from hay fever or allergic-type symptoms such as an itchy rash or bite on the skin or redness and minor skin swelling, then an antihistamine may help relieve these symptoms.

Minor allergic reactions to products (washing detergent, creams, perfume) and food or plant reactions (stinging nettles) can be safely treated with over-the-counter antihistamines. They should get better in hours to days. Make sure to avoid whatever causes the reaction in the future.

If you find that you are getting regular allergic reactions and do not know why, you should discuss it with your doctor, and you may benefit from getting allergy testing.

Histamine is a naturally occurring chemical in the body that is activated and released from your cells when a foreign substance triggers your immune system. Histamine sets off a chain reaction, allowing your immune system to detect and remove the thing that caused it.

While a useful and important response, the release of histamine causes redness, swelling, and itchiness that can be bothersome. Individuals that suffer from hay fever or show allergic sensitivity to harmless stimuli have a higher-than-normal amount of histamine released by the immune system.

Antihistamines help prevent and reduce histamine's effect in the body and therefore are effective at relieving allergic symptoms.

Antihistamines can be classified as drowsy or non-drowsy. Chlorpheniramine and diphenhydramine can make you drowsy. Care should be exercised when driving or operating heavy machinery, and alcohol should be avoided. Some antihistamines that cause drowsiness, such as diphenhydramine, are also found in over-the-counter sleeping tablets.

Some other over-the-counter antihistamines are classed as non-drowsy: cetirizine (Zyrtec), levocetirizine (Xyzal), loratadine (Claritin) and fexofenadine (Allegra). These are less likely to cause drowsiness, but it is still a possible side effect.

Different medications have different doses and schedules for how often you can take them. Check with your pharmacist or read the box carefully if unsure.

Most antihistamines are safe for long periods, for example, throughout hay fever season. However, chlorphenamine should not be used for more than two weeks without consulting a doctor. Antihistamine creams are also available and may be more suitable for treating localized reactions such as insect bites.

Talk to your doctor if you are pregnant or breastfeeding before taking antihistamines. Do not take antihistamines three days before taking an allergy skin test, as this can affect your results. Do not take drowsy antihistamines if you have breathing problems, glaucoma, or an enlarged prostate.

Like all medications, don’t take it if you have previously had an allergic reaction to the medication, if you have severe kidney or liver problems, or if you have other medications or medical conditions that you would normally discuss with your doctor or pharmacist before starting something new.

Side effects from antihistamines can vary based on the type and how a person responds to them. While many people use them without issues, certain effects are worth knowing.

First-Generation Antihistamines

These older medications, like diphenhydramine and chlorpheniramine, can make you feel sleepy because they cross into the brain.

Common Symptoms

Fatigue, dry mouth, and blurred vision are typical. Some users also report dizziness or a sluggish digestive system leading to constipation. Urinary retention might occur in some individuals.

Occasional Reactions

Less often, these drugs can cause excitement rather than drowsiness, particularly in children. Older adults may experience confusion or trouble thinking clearly.

Second-Generation Antihistamines

Newer options like loratadine and cetirizine generally avoid crossing into the brain, so sedation is less of an issue.

Mild Effects

Some people may still feel a bit drowsy, especially with cetirizine. Headaches or dryness in the mouth can occasionally occur but are usually short-lived.

More Serious Effects

Rapid heartbeat or digestive upset has been noted but is infrequent.

Additional Considerations

Pregnancy and Breastfeeding - Not all antihistamines are safe during these times. Some can transfer into breast milk, potentially affecting the baby.

Drug Interactions - Combining first-generation antihistamines with alcohol or sedatives can heighten drowsiness.