Since histamine has a large amount of functions within the human body, the effects of high histamine blood levels can vary widely. I’ve scoured the net to make a good list of these and provide a short explanation as to why histamine causes these. I’d like to go into these in more detail in later posts. Some of these are widely known and proven by science, others I didn’t put through the scholar search engines yet, but I will try to continuously update this post every time I find out more.
Symptoms affecting muscles
Histamine affects smooth muscle, which acts autonomously, histamine is the main controlling agent for contractions within this type of muscle. But it can also cause reactions within other types of muscle,
Bladder – As the bladder is made out of smooth muscle, contractions can occur, often people suffer from a weak bladder resulting in needing to pee often.
Bronchioconstriction/wheezing – Smooth muscle is also located in the airways, leading to asthmatic symptoms.
Gastrointestinal trouble - The same goes for the bowel and colon which is mostly made out of smooth muscle. Spasm’s and irritable bowel syndrome can be caused by histamine. As are many other problems. Diarrhea or constipation, bloating, cramps, abdominal pain and nausea to name a few eh.. well most.
dysmenorrhea (menstruation pain) – The uterus consists of smooth muscle, and a heightened amount of histamine can cause more severe menstruation cramps in women. As histamine also tampers with hormonal levels like progesterone and oestrogen, which in turn can influence levels of histamine. The good news is that the placenta in pregnant women produces large amounts of DAO leading to a remission of the intolerance during pregnancy.
Blood pressure and flushing – Smooth muscle is located in the blood vessel, so histamine affects the dilation of blood vessels and the permeability as well. Leading to a variety of symptoms like high or low blood pressure, as well as flushing (blushing) of the skin.
Hyves/eczema/urticaria – These often are immunological responses, but can be caused or exacerbated by high levels of histamine.
Heart tachycardia - Histamine is also present in the heart, and heart rhythm failures and palpitations can be caused by histamine. If histamine is the cause of this, there is no presence of other heart disease.
(Fibro)myalgia- It also plays a role in the functioning of other muscles, Leading to muscle aches even without a cause, and also (fibro)myalgia symptoms.
Muscle cramps and spasms – As said it’s import in muscle functioning. It can also cause cramps and spasms of non-smooth muscle mass and muscle soreness. The release of nitrite oxide stimulated by histamine is the main cause of this.
Pain – Histamine decreases the threshold of pain receptors to feel pain, as it sensitizes the pain receptors.
Itch – Histamine stimulates sensory nerve endings which can cause itching.
Headache/migraine – As histamine stimulates the release of nitrate monoxide, it can cause slight headaches to full-blown migraine attacks.
Joint pain/rheumatic problems – The main cause of these are infections and the holding of fluid, since histamine does exactly does things, these kind of problems will arise as well.
Stomach Acid/Ulcers – Histamine also steers the production of stomach acid, leading to ulcers and other disorders of the stomach. Frequent hiccups are one example of this.
Allergies/sickness - As histamine is an important messenger molecule in immunological responses. it can cause the same symptoms as allergies or a real invasion of some sort can cause.
Mucus secretion – As well as stimulating gastric acid, it also stimulates other mucus secretions, saliva, mucus of the nose, mucus within the airways and tears.
Dark circles under the eyes – these results because of the direct influence of histamine on vasodilation, but also the itch histamine can cause leads to scratching and rubbing around the eyes can exacerbate these even more.
Eyesight – Eyesight troubles can occur, making the eyes more and less sensitive to light, as well as interfere with the ability to contract eye muscles and with vasodilation contracting of fluids, the shape of the lens of the eye can change. Resulting in less than perfect vision.
Sweating – Histamine also plays a role in different ways in the regulation of sweat, and most of all the occurrence of sweating.
Hairloss – histamine is also related to the induction of hair loss, by continual inflammation follicles can stop producing hair. This can also result from inner stress and tension occurring direct or indirectly from a high level of histamine.
Fatigue - as the adrenal gland reacts upon histamine within the blood by releasing cortisol, this gland can get exhausted leading to fatigue. The antagonistic effect of adrenaline on histamine as well can cause feelings of fatigue.
Central nervous system
Most of these symptoms just mentioned are within the general body, but histamine also has major functions within the central nervous system. Even though I often see mentioned it doesn’t or badly diffuses through the blood-brain-barrier, it does affect the permeability of the blood brain barrier and as such I figure histamine will be able to cross is. And as certain symptoms t stem from a feedback system from the rest of the body to the central nervous system which leads to certain reactions with the nervous system. This could be the cause for other symptoms as well.
Thirst – As neurotransmitter histamine is part of the management of water intake and distribution throughout the body it is released if dehydration occurs. As such excessive levels of histamine can occur due to dehydration itself. It will make you crave for fluids, food and carbohydrates (as these help in the distribution of water).
Lack of appetite - Even though in the regulation of water intake histamine plays a role in the need for food, which contains water, it also suppresses hunger. If the gastrointestinal problems in itself didn’t yet do so.
Nausea – Histamine mediates the sending of nausea signals from the body to the brain. And also stimulates the ‘vomiting’ center in the brain. Leading to nausea and vomiting.
Dizziness/Vertigo - Most of these stem from inner ear troubles. Even though in some cases histamine itself can give relief from this. It can also cause dizziness. As it affects the vestibular responses.
Arousal/insomnia/anxiety – These are in my opinion closely related even though different brain areas are involved. One major function of histamine is in an area of the brain that’s active when awake, it controls wakefulness and circadian rhythm, another one is the anxiety center. There closely correlate in being awake, wakeful, and vigilant for threats. This can lead to insomnia, and anxiety attacks.
Nightmares – Though it is unknown where this stems. I figure the stimulation of the anxiety center and the increase of anxiety can result in nightmares.
Crying - Tears also function as a way to flush stress molecules and toxins from the body. This, the anxiety, and production of tears caused by histamine, can lead to persons being more prone to start crying.
Depression – Histamine inhibits the release of serotonin, leading to the occurrence of depression. In combination with the detrimental effects on healths this occurs even more easily.
Memory – As histamine plays an important role within memory storage and retrieval, problems with memory can occur.
Other trouble that can occur
Weight problems – As metabolism is influenced in a variety of ways by a lot of factors, like immunological stress and other stress factors. The presence of gastrointestinal problems can lead to a lack of nutritional uptake from the bowels. Overstressing of the liver as well, can lead to an excessive storage of fat. Recently an article appeared in which a woman suffered from anorexia was described, but instead of anorexia she suffered from histamine intolerance.
Sexual disorders - With the functions of histamine in vasodilation and arousal, it plays a major role in arousal of mind and body. Leading to high libido and making it easier to achieve orgasm. Especially in males this can lead to premature ejaculation
Adrenaline/panick attacks/fatigue – Adrenaline counteracts the functions of histamine, and vice versa. As histamine increases adrenaline will as well. Messing up chemistry in body and brain even more. Causing panic attacks. fatigue etc.
Sensitivity to stress – As mean there are quite some effects histamine has which can lead to stress sensitivity. One more is that stress itself can cause release of histamine. If there is a high level of histamine, than a little bit of extra released histamine can quickly lead to more severe reactions.
Sensitivity to other factors – A lot of other factors will release histamine, heat, cold, pollen, aggravation of the skin and such, will lead to more severe oversensitive reactions in those with high levels of histamine.
Alcohol intolerance - Alcohol often contains a lot of histamine, leading to any histamine intolerance symptoms. And alcohol also has an inhibiting effect on the activity of one of the enzymes breaking down histamine, which can lead to worse symptoms, and more sensitive reactions over a longer period of time.
Other possible symptoms and comorbities
Restless leg syndrome – As histamine mediates in alertness and wakefulness. It is found that people with restless leg syndrome often have more histamine H2 and H3 receptors within their brain. More histamine can exacerbate and cause this syndrome. Though anti-histamines can also worsen and cause restless legs.
Ménière’s Disease- Ménière is disorder of the inner ear, often due to the containment of fluids within it. histamine can also lead to too much fluid within the inner ear. And lead to Ménière symptoms. As can too little histamine.
ADD/ADHD – ADD and ADHD tend to stem from a lack of dopamine in the brain. As histamine inhibits the release of dopamine, this can lead to ADD and ADHD like symptoms. Other effects of histamine on neurotransmitters and the brain can lead to these symptoms as well. People that suffer from ADD and ADHD often show higher histamine levels.
Autism – Even though histamine doesn’t cause autism, it can cause autism like symptoms due to the effect is has on body and brain. Often people with autism suffer from higher histamine levels which exacerbates some of the problems they have.
OCD – It is also said that histamine can cause OCD or worsen it. With the anxiety and arousal, can also lead to perfectionistic tendencies.
Schizophrenia – schizophrenics often show high or low levels of histamine. It is though that some functions of histamine can set of a psychotic episode in schizophrenics.