Histamine is a natural chemical produced by the immune (disease-fighting) system of the body. When it is released, it increases blood flow to the affected area. Liquid leaks out of the blood vessels, making the mucous membranes lining the nose and throat to swell, and stimulating nearby gland to produce mucus. It causes symptoms such as itching, swelling, or reddening. Histamine can also cause sneezing, running nose, itchy or watery eyes, and in some people can cause breathing difficulties.

Histamine is involved in a variety of physiologic responses, such as inflammation, type I allergy, gastric acid secretion, and neurotransmission.

Natural supplements that have antihistamine action
There are quite a number of herbs that have shown natural antihistamine action in lab studies, however few human trials are available to tell us how effective these "herbal antihistamines" are work when ingested as a supplement. I will present a few options but keep in mind that this is by no means an endorsement of these herbs. I just want people to know that there are some herbs that have potential and hopefully future research will give us some additional clues about natural antihistamine herbs and nutrients.

Butterbur is a supplement available orally.

Curcumin and turmeric
Korean J Physiol Pharmacol. 2018. Antipruritic effect of curcumin on histamine-induced itching in mice. Histamine-induced itching can be blocked by topical application of curcumin through the inhibitory action of curcumin on TRPV1 receptors in peripheral nerves.

Mangosteen is a fruit extract supplement usually sold in juice form or as capsules.

The Effect of a Herbal Water-Extract on Histamine Release from Mast Cells and on Allergic Asthma.
J Herb Pharmcother. 2003.
A water extract of a mixture of eight herbs (chamomile, saffron, anise, fennel, caraway, licorice, cardamom and black seed) was tested for its inhibitory effect on histamine released from rat peritoneal mast cells stimulated either by compound 48/80 or be IgE/anti-IgE. The effect of the herb extract was compared to that of the flavonoid quercetin. The herbal water-extract inhibited histamine released from chemically- and immunologically-induced cells by 81% and 85%, respectively; quercetin treated cells were inhibited by 95% and 97%, respectively. The clinical results showed significant improvements of sleep discomfort, cough frequency and cough intensity in addition to increased percentages of FEV₁/FVC in patients suffering from allergic asthma, who used the herbal tea compared to those who used the placebo tea.

For more information on natural antihistamines, see allergy or allergic rhinitis.

Asian Pac J Trop Med. 2011. Phytopharmacological evaluation and anti-asthmatic activity of Ficus religiosa leaves. To discuss phytopharmacological potential and anti-asthmatic activity of Ficus religiosa (F. religiosa) (L.). Fresh leaves of F. religiosa were obtained from Vastrapur Lake, Ahmedabad, and dried to obtain powder. Histamine and acetylcholine were used to guinea pigs to establish bronchospasm model. In in vivo study, the aqueous extract of F. religiosa leaves (AEFR) at doses of 150 and 300 mg/kg was administrated to guinea pigs, and the broncho-protective activity of AEFR was compared with aminophylline at 25 mg/kg. While in in vitro study, and 10 g/mL, 20 g/mL, 30 g/mL of AEFRL was administrated to guinea pigs, respectively, and mast cell stabilizing activity of AEFR was compared with ketotifen at 10 g/mL. In the in-vivo model, pre-treatment with aminophylline (25 mg/kg, ip.) could significantly delay the onset of histamine induced pre-convulsive dyspnea, compared with vehicle control. Administration of AEFRL (150 and 300 mg/kg, ip.) also produced significant effect on latency to develop histamine & acetylcholine induced pre-convulsive dyspnea. In the mast cell stabilizing model, AEFRL at 10, 20 and 30 μg/mL could significantly increase the number of intact cells. It can be concluded that AEFRL is effective on histamine & acetylcholine induced bronchospasm in guinea pigs. In addition, AEFRL can potentiate the number of intact cells in the mast cell stabilizing model.

West Indian Med J. 2015. Preliminary Investigations of the Anti-asthmatic Properties of the Aqueous Extract of Justicia pectoralis (Fresh Cut). Justicia pectoralis (fresh cut), family Acantheceae, is a herb that is native to central America and the Caribbean. A crude extract prepared from the leaves of Justicia pectoralis is commonly used in Jamaican ethnotraditional medicine to reduce difficulty in breathing and suppress wheezing in asthmatic individuals. To investigate the anti-inflammatory and antihistamine activity of an aqueous extract of Justicia pectoralis. A crude extract of the leaves Justicia pectoralis reduced the formation of histamine-induced wheals in sensitized guinea pigs (p < 0.05) and also reduced histamine-induced tracheal smooth muscle contractions. It blocked the effect of contraction produced by histamine in the airways; this property supports folklore claims for its use as an antihistamine. In addition, Justicia pectoralis extract reduced the size of histamine-induced wheals in the dermis.

Antihistamine drugs and their medical uses
Antihistamine drugs are used to stop the effects of histamine, most often used to stop a runny nose or skin allergy. Antihistamine drugs are most often used to treat allergic reactions, although certain types can be used in the treatment of other conditions such as migraines, travel sickness, and stomach ulcers. Antihistamine drugs are available as tablets, creams, and injections. There are over the counter antihistamine drugs and also antihistamine drugs by prescription. The older antihistamines, such as Benadryl, tend to cause drowsiness and rare dangerous heart arrhythmias (terfenadine and astemizole). More recently developed, new antihistamines, cause less drowsiness but may still cause heart rhythm problems. It is difficult to mention the best antihistamine since each person will have their own preference.

Antihistamine side effects, long term risk
Antihistamine medications can produce some unpleasant side effects. Common antihistamine side effects include drowsiness, dry mouth, difficulty in urination, and constipation. An overdose could cause excessive sedation and heart rhythm irregularities. The newer non drowsy antihistamines are an option for those who need to take them during the day. However, I suggest using these medicines as little as possible to reduce the potential side effects. It is probably best not to use an antihistamine during pregnancy unless absolutely required.

People taking products with diphenhydramine such as Benadryl may increase their risk for mental impairment. Benadryl blocks the neurotransmitter acetylcholine and interrupts the normal functioning of the central and peripheral nervous systems. The more a person uses it, the more of a negative effect this will have on the nervous system.

Antihistamine and decongestant
Many products on the market have an antihistamine and decongestant combined. I think these pills may be appropriate for those who have nasal allergies, but a combination antihistamine and decongestant is not appropriate for treating the common cold since there is no allergy involved in the common cold.

Metabolism
Histidine decarboxylase is the rate-limiting enzyme for mammalian histamine synthesis. Histamine is a multifunctional biogenic amine with relevant roles in intercellular communication, inflammatory processes and highly prevalent pathologies. Histamine biosynthesis depends on a single decarboxylation step, carried out by a PLP-dependent histidine decarboxylase activity.

Histamine in food
Histamine is a biogenic amine that occurs to various degrees in many foods. In healthy persons, dietary histamine can be rapidly detoxified by amine oxidases, whereas persons with low amine oxidase activity are at risk of histamine toxicity. Diamine oxidase is the main enzyme for the metabolism of ingested histamine. Some people may have histamine intolerance if they cannot breakdown histamine from foods fast enough.

Foods high in histamine (including fermented foods) include alcoholic beverages, especially beer, champagne and wine, anchovies, avocados, cheeses, especially aged or fermented cheese, such as parmesan, blue and Roquefort, dried fruits such as apricots, dates, figs, prunes, and raisins, fermented foods such as pickled or smoked meats, sauerkraut, etc., mushrooms, processed meats such as sausage, hot dogs, salami, etc., sardines, smoked fish such as herring, sour cream, sour milk, buttermilk and yogurt - especially if not fresh, soured breads, such as pumpernickel, coffee cakes and other foods made with large amounts of yeast, spinach, tomatoes, vinegar or vinegar-containing foods, such as mayonnaise, salad dressing, ketchup, chili sauce, pickles, pickled beets, relishes, olives.

Foods that release histamine include alcohol, bananas, chocolate, eggs, fish, milk, papayas, pineapple, shellfish, strawberries, and tomatoes.

Natural antihistamine research
Inhibitions of histamine release and prostaglandin E2 synthesis by mangosteen, a Thai medicinal plant.
Biol Pharm Bull. 2002.
The fruit hull of mangosteen has been used as a Thai indigenous medicine for many years. However, the mechanism of action of mangosteen as a medicine has not been elucidated. The present study was undertaken to examine the effects of mangosteen extracts (100% ethanol, 70% ethanol, 40% ethanol and water) on histamine release and prostaglandin E2 synthesis. We found that the 40% ethanol extract inhibited IgE-mediated histamine release from RBL-2H3 cells with greater potency than the water extract of Rubus suavissimus that has been used as an anti-allergy crude drug in Japan. All extracts of mangosteen potently inhibited A23187-induced prostaglandin E2 synthesis in C6 rat glioma cells, while the water extract of Rubus suavissimus had no effect. The 40% ethanol extract of mangosteen inhibited the prostaglandin E2 synthesis in a concentration-dependent manner with relatively lower concentrations than the histamine release. In addition, passive cutaneous anaphylaxis (PCA) reactions in rats were significantly inhibited by this ethanol extract as well as by the water extract of Rubus suavissimus. These results suggest that the 40% ethanol extract of mangosteen has potent inhibitory activities of both histamine release and prostaglandin E2 synthesis.

Questions
I always read your website about all of the products that you talk about, and I find it very informative. I was wondering if you knew anything about Histadelia, a disorder characterized by high histamine levels. I was wondering if you knew anything about it, and if so, then what supplements or nutrients would you recomend taking? Whenever I search for Histadelia on the net, I always seem to run across another keyword: "pyroluria". If you could help me out with these questions, I would be very grateful!!!!
   I have not studied histadelia or pyroluria, but if you do a search on google and find out all the web pages where histamine is mentioned. Try these words in google: histamine site:raysahelian.com

I recently bought a book called 'The complete guide to vitamins herbs and supplements' by winifred Conkling w/ david  y. Wong, m.d., consulting editor. In it concerning impotence it said some over-the counter antihistamines and decongestants can cause temporary impotence, but can they also cause testosterone levels to drop ,if so can the effects of long term use of these be reversed ?.
   It is true that in some people decongestants and antihistamines can cause impotence, but it is unlikely that it is due to testosterone. Many people find sexual enhancement with herbs and supplements that can reverse this condition.

I get an allergic response (sinus problems, skin rash) to oral carnosine at 500-1000mg.  I believe it's a histamine release but I find it strange.
   Carnosine converts into histidine which converts into histamine. Perhaps too high of a carnosine dose can shift the metabolic pathway towards histamine.

I have found an antihistamine to be a very effective sleeping pill without hangover and I don't think there's addiction. Is there any problem with taking antihistamines for sleep? How about for a long period or time?
   Most drugs have side effects. Long term antihistamine use can lead to tolerance, but whether the older antihistamines have cardiac effects in the long run is difficult to tell at this time. The newer H2 blockers may have cardiac side effects.

I've read several books by Harold N. Levinson, M.D., a psychiatrist & neurologist, more specifically Phobia Free and Smart but Feeling Dumb. I just wondered if you were familiar with his treatment for dyslexia and phobias, caused by inner ear problems, using small combined doses of vitamin supplements, antihistamines, anti-motion sickness drugs, antidepressants, etc. I don't like to take any medicine, whether otc or not, and wondered if, after reviewing some of his work, if you would suggest natural alternatives to these otc and regular meds that would help with inner ear problems. Some of the natural supplements that you recommend for ADD are the same that he recommends for balance and coordination (physical and mental) problems common to dyslexic patients. More specifically, what natural supplements work like an antihistamine in helping with an inner ear dysfunction caused by fluid in the ear?
    This area has not been studied well but perhaps some of the info on this site may be helpful.