# Do antihistamines affect heart rate

**URL:** https://boards.straightdope.com/t/do-antihistamines-affect-heart-rate/319154
**Category:** Factual Questions
**Created:** [August 29, 2005, 8:49pm UTC](https://boards.straightdope.com/t/do-antihistamines-affect-heart-rate/319154 "2005-08-29T20:49:19Z")
**Posts on this page:** 4
**Page:** 1

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### Author: ![Wesley\_Clark](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/wesley_clark/32/20581_2.png) [@Wesley\_Clark](https://boards.straightdope.com/u/Wesley_Clark)
#### Post date: [August 29, 2005, 8:49pm UTC](https://boards.straightdope.com/t/do-antihistamines-affect-heart-rate/319154/1 "2005-08-29T20:49:19Z")

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Do antihistamines cause your heart rate to go up? I donate plasma and I am worried that if I take one it will cause my heart rate to go too high and I won’t be able to donate. Is there a risk that they can change pulse rates?

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### Author: ![pinkfreud](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/pinkfreud/32/17603_2.png) [@pinkfreud](https://boards.straightdope.com/u/pinkfreud)
#### Post date: [August 29, 2005, 9:14pm UTC](https://boards.straightdope.com/t/do-antihistamines-affect-heart-rate/319154/2 "2005-08-29T21:14:19Z")

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Most antihistamines have sedative side-effects. Decongestants can act as stimulants, though, and may increase your heart rate.

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### Author: ![DeVena](https://avatars.discourse-cdn.com/v4/letter/d/dec6dc/32.png) [@DeVena](https://boards.straightdope.com/u/DeVena)
#### Post date: [August 29, 2005, 9:22pm UTC](https://boards.straightdope.com/t/do-antihistamines-affect-heart-rate/319154/3 "2005-08-29T21:22:14Z")

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[Great website from NIH about antihistamines.](http://www.nlm.nih.gov/medlineplus/druginfo/uspdi/202060.html)

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### Author: ![Qadgop\_the\_Mercotan](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/qadgop_the_mercotan/32/83_2.png) [@Qadgop\_the\_Mercotan](https://boards.straightdope.com/u/Qadgop_the_Mercotan)
#### Post date: [August 29, 2005, 11:57pm UTC](https://boards.straightdope.com/t/do-antihistamines-affect-heart-rate/319154/4 "2005-08-29T23:57:43Z")

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It is uncommon for antihistamines to alter someone’s heart rate, but it can and does happen.

It is far more common to have decongestants (particularly pseudoephedrine) cause an increase in one’s heartrate.

Many people are confused, and claim they take antihistamines when they really take a decongestant, or an antihistamine/decongestant combination.