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What are the Most Common Antihistamine Side Effects?

Anna T.
Anna T.

Drowsiness is typically considered to be the most common of all the antihistamine side effects. The majority of antihistamine medicines, many of which are available over the counter, have the ability to make a person feel very sleepy. In addition to sleepiness, antihistamines are also capable of causing urination difficulty along with dryness of the mouth and eyes. Older antihistamines, which are frequently referred to as first-generation antihistamines, are much more likely to cause these side effects. Many people who take second- and third-generation antihistamines do not experience antihistamine side effects at all.

Antihistamines may not affect every person in the same way, and some people are naturally more sensitive to them than others. People who are incredibly sensitive to antihistamines should use caution when taking them. Driving and operating any type of heavy machinery should typically be avoided by people who frequently experience antihistamine side effects. Alcohol and antihistamine use do not usually mix well because alcohol can make a person's drowsiness worse when he is taking antihistamines. Most doctors tell patients to take their antihistamines before going to bed rather than throughout the day, particularly if their patients are sensitive to the medication.

Potential side effects of some antihistamines include daytime drowsiness and dry eyes.
Potential side effects of some antihistamines include daytime drowsiness and dry eyes.

There are some people who should avoid using antihistamines unless their doctors prescribe them. Antihistamines have not been proved safe for use in pregnant women, and doctors typically advise their pregnant patients against taking them. Men who suffer from an enlarged prostate may also need to avoid antihistamine use unless their doctors recommend them. People who tend to retain urine may also need to avoid antihistamines because the drug by itself tends to cause urine retention, and it could make a person's symptoms much worse if she already suffers from that problem. Doctors do occasionally prescribe antihistamines for children, but normally do so with great caution; antihistamines may not be prescribed at all for babies and toddlers.

Antihistamines help clear up runny noses, sneezing, and more.
Antihistamines help clear up runny noses, sneezing, and more.

In spite of the potential antihistamine side effects that some people experience, antihistamines are often very helpful for controlling allergy symptoms. The fact that antihistamines can cause drowsiness might actually be considered a benefit to a person who is having trouble sleeping due to a cold or allergies. Antihistamines are considered very useful for helping with runny noses, sneezing, and itchy eyes and nose resulting from allergies. People who have itching that resulted from other causes, such as insect bites or eczema, might also find relief from antihistamine use. A person who has ever had any serious health problems or is on some type of prescription medication should probably talk to his doctor before taking antihistamines to be sure they are safe for him.

Discussion Comments

Pippinwhite

@Lostnfound -- I know what you mean about the drowsiness. I've been known to fall asleep at my desk after taking some cold medicines! Not terribly conducive to maintaining a professional office demeanor.

Lostnfound

Fewer side effects or not, I always choose a "no drowsiness" formula if I have to take an antihistamine, especially during the day. That's when I really need it.

I will say that most antihistamines on the market nowadays are generally better and not as likely to make me drowsy. I think the dry mouth issue is going to persist, just because they tend to dry you out, but the no-drowsiness formulas do seem to work pretty well.

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    • Potential side effects of some antihistamines include daytime drowsiness and dry eyes.
      By: Alliance
      Potential side effects of some antihistamines include daytime drowsiness and dry eyes.
    • Antihistamines help clear up runny noses, sneezing, and more.
      By: taisiya1985
      Antihistamines help clear up runny noses, sneezing, and more.
    • Men who suffer from an enlarged prostate may need to avoid antihistamine use unless their doctors recommend them.
      By: peterjunaidy
      Men who suffer from an enlarged prostate may need to avoid antihistamine use unless their doctors recommend them.
    • Some people struggle to stay awake when taking antihistamines.
      By: oporkka
      Some people struggle to stay awake when taking antihistamines.
    • Antihistamines can often stop dangerous effects of an allergic reaction, including throat swelling.
      By: jinga80
      Antihistamines can often stop dangerous effects of an allergic reaction, including throat swelling.
    • Antihistamines should not be taken by pregnant women.
      By: Alliance
      Antihistamines should not be taken by pregnant women.