# Decongestant or Antihistamine? **URL:** \ **Category:** Factual Questions\ **Created:** [December 22, 2007, 9:20am UTC](https://boards.straightdope.com/t/decongestant-or-antihistamine/430918 "2007-12-22T09:20:05Z")\ **Posts on this page:** 6\ **Page:** 1
**Author:** ![Jinx](https://avatars.discourse-cdn.com/v4/letter/j/c6cbf5/32.png) [@Jinx](https://boards.straightdope.com/u/Jinx)\ **Post date:** [December 22, 2007, 9:20am UTC](https://boards.straightdope.com/t/decongestant-or-antihistamine/430918/1 "2007-12-22T09:20:05Z")
In our house, it is an age-old argument. What IS the difference? As I understand it, a cold triggers the cells to overproduce histine which leads to an abundance of histamine which, supposedly, makes our noses run, etc. So, it seems logical an antihistamine is the answer. Yet, a decongestant does not contain antihistamine! So, what’s the deal here? Any SDopers in pharmacy or bio-chem? - Jinx ---
**Author:** ![ParentalAdvisory](https://avatars.discourse-cdn.com/v4/letter/p/53a042/32.png) [@ParentalAdvisory](https://boards.straightdope.com/u/ParentalAdvisory)\ **Post date:** [December 22, 2007, 9:47am UTC](https://boards.straightdope.com/t/decongestant-or-antihistamine/430918/2 "2007-12-22T09:47:07Z")
[QUOTE=Jinx] Any SDopers in pharmacy or bio-chem? [/QUOTE] No, but at first glance, it seems a decongestant is used to relieve swollen membranes or blockage, and an antihistamine would be what you would use to prevent histamine like you said from allergies or colds. ---
**Author:** ![Napier](https://avatars.discourse-cdn.com/v4/letter/n/ce73a5/32.png) [@Napier](https://boards.straightdope.com/u/Napier)\ **Post date:** [December 22, 2007, 3:34pm UTC](https://boards.straightdope.com/t/decongestant-or-antihistamine/430918/3 "2007-12-22T15:34:20Z")
Right, decongestants generally work by vasoconstriction, in which they tighten the blood vessels to reduce their leakage of blood serum (which is the mechanism by which mucus membranes excrete), whereas antihistamines generally work by blocking one of the several steps in the immune system’s histamine response. ---
**Author:** ![KarlGauss](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/karlgauss/32/3713_2.png) [@KarlGauss](https://boards.straightdope.com/u/KarlGauss)\ **Post date:** [December 22, 2007, 7:27pm UTC](https://boards.straightdope.com/t/decongestant-or-antihistamine/430918/4 "2007-12-22T19:27:48Z")
[QUOTE=Jinx] In our house, it is an age-old argument. What IS the difference? As I understand it, a cold triggers the cells to overproduce histine which leads to an abundance of histamine which, supposedly, makes our noses run, etc. So, it seems logical an antihistamine is the answer. Yet, a decongestant does not contain antihistamine! So, what’s the deal here? Any SDopers in pharmacy or bio-chem? - Jinx [/QUOTE] As others have said, antihistamine medicines may be of some use for symptoms due to allergy. Although, by virtue of the near-ubiquitous presence of antihistamines in cold and flu remedies, the drug companies would have you believe they’re also of benefit in those conditions as well, there is, in fact, virtually no evidence that antihistamines are effective to relieve the symptoms of colds. At the bottom of [this page](http://www.aafp.org/afp/20040801/cochrane.html), is a beautifully concise summary\* of the evidence with respect to antihistamines and the common cold. As you can see, there really is not very much evidence at all. I’ll point out that you’re more likely to be sedated by antihistamines than you are to obtain relief of cold symptoms from them. Indeed, their purported benefit may simply be a result of people “mistaking” ease of sleep following their use rather than their effectiveness in treating a cold. Note also that the newer, nonsedating antihistamines have _not_ been shown to be of any benefit whatsoever for treating the common cold. That provides additional proof that any benefit of antihistamines for cold symptoms is simply a result of their sedating properties. \*these Cochrane Reviews are about as good as it gets in terms of locating, appraising, and distilling the evidence for topics in clinical medicine. ---
**Author:** ![beagledave](https://avatars.discourse-cdn.com/v4/letter/b/6de8d8/32.png) [@beagledave](https://boards.straightdope.com/u/beagledave)\ **Post date:** [December 22, 2007, 11:38pm UTC](https://boards.straightdope.com/t/decongestant-or-antihistamine/430918/5 "2007-12-22T23:38:27Z")
[QUOTE=KarlGauss] there is, in fact, virtually no evidence that antihistamines are effective to relieve the symptoms of colds. [/QUOTE] What about this > **[Common Cold](https://commoncold.org)** > > A comprehensive source of information on the common cold that facilitates informed decisions about cold prevention and treatment. > [@](#): > > The effectiveness of first generation antihistamines for sneezing, runny nose, and possibly cough has been impressive in recent clinical trials. (21-23) NSAIDs are effective for general cold symptoms such as feverishness, headache, and not feeling well and may be of benefit for controlling coughs. (26-28) A first generation antihistamine taken with an NSAID provides a sound basis for an initial cold treatment that will give relief of most cold symptoms. More discussion here > **[Common Cold](https://commoncold.org)** > > A comprehensive source of information on the common cold that facilitates informed decisions about cold prevention and treatment. > [@](#): > > Early studies of the first generation antihistamines for the treatment of colds gave negative results because of inadequate precision in recording of cold symptoms. The results of these studies are now known to be incorrect. > > Recent studies of first generation antihistamines for treatment of colds employed careful recording of individual cold symptoms on a day-by-day basis. (21-23) These studies showed that first generation antihistamines are quite effective in reducing the sneezing and runny nose of colds. Measured nasal weights were also reduced. One of the antihistamines tested, brompheniramine, reduced the frequency and severity of cough. (23) ---
**Author:** ![Philster](https://avatars.discourse-cdn.com/v4/letter/p/13edae/32.png) [@Philster](https://boards.straightdope.com/u/Philster)\ **Post date:** [December 23, 2007, 12:02am UTC](https://boards.straightdope.com/t/decongestant-or-antihistamine/430918/6 "2007-12-23T00:02:48Z")
Antihistamines are downers and decongestants are uppers.