Does antihistamine make you drowsy?

Older ones do. First generation antihistamines (benadryl, clor-pheramine, atarax) cross the blood brain barrier and cause lethargy. Second generation (allegra, claritin, zyrtec, xyzal, (levocetirizine) clarinex) cause the blood brain barrier at a much lesser amount and more targeted to the h1 receptor.

Related Questions

Why do some antihistamines make me drowsy?

Cross into brain. Older antihistamines, such as diphenhydramine, or chlorpheniramine, actually cross the barrier between the bloodstream and the brain. This causes many people to feel drowsy or sedated. It can make some people irritable, or even cause insomnia. For this reason, the "non-sedating" antihistamines were developed. These medications cause much less drowsiness, and are better tolerated. Read more...
Antihistamines. Because they cross the blood brain barrier and trigger receptors that can lead to sedation. The only one that does not cross the blood brain barrier is allegra/fexofenadine. Read more...

Why does drowsiness occur after taking antihistamines?

Complex. Histamine is a wake promoting neurotransmitter in the brain. Older antihistamines like Benadryl (diphenhydramine) cross into the brain and block this center allowing for drowsiness to occur. The newer antihistamines like alleges, claritin, zyrtec do not cross as easily and are less likely to promote drowsiness. Read more...
Blood Brain Barrier. Any antihistamine that crosses the blood brain barrier can cause sedation and drowsiness. There are at least four types of histamine receptors in the body and they can be acted on as well. There are also 1st generation and 2nd generation antihistamines which have varying drowsy classifications. Read more...

Can drowsiness caused by antihistamines be treated or minimized at a necesary event?

Yes but. A decongestant is often added to antihistamine and would counteract some of the drowsy effects but that is not a good solution. There are at least two other non-drowsy antihistamines available and steroid nasal spray actually works far better without the drowsy effect. If your only choice is a sedating antihistamine, take it an hour before you go to bed instead of the morning. Read more...

How can I safely test to see if an antihistamine produces drowsiness? I know even the new generation has this side effect.

Wait until a day. when you don't have to go to school (weekend) and try it. It's the only way to know. Take the smallest dose available and see if it works. Read more...

Can a non drowsy antihistamine that had no side effects that I've noticed hurt you if u take 2 pills in 24hrs instead of 2?

No. Which antihistamine? Why using it? Sometimes, for chronic urticaria, cetirizine [Zyrtec] is dosed at 3 a day . The official dose of these is 1 a day. Allegra and claritin are also sometimes used at double or triple dose.It is best if you consult a Dr before you take doses higher than usual. Read more...

What is an extra drowsy antihistamine I can ask my doctor for?

Benadryl (diphenhydramine) The classic antihistamine, which has always had a very high incidence of drowsiness. In fact, due to its safety, has been used on occasion as a sleeping aide. Read more...

Bitten by unknown insect. Redness and swelling to forarm. Marked with pen and doubled in size over 36hrs. Taking non drowsy antihistamines and icing?

Ice. Benadryl (or your choice of a non-sedating antihistamine such as Zyrtec, Claritin, or Allegra), ice, and ibuprofen is a good initial treatment for insect bites. Infection is a possible delayed complication. If you develop a boil, a discolored blister, fever, increasing pain, or other concerning signs, see a physician for an exam. Read more...