A histamine imbalance is another way of saying that there is too much or too little of the histamine chemical in the brain. Because our bodies require a specific amount to function properly, histamine imbalances have both mental and physical side effects.
Histamine is, according to Naturopathic Care, an "important brain chemical and is involved in all sorts of reactions including those to pain, allergies, mucus and saliva production, causing tears to flow and other body secretions." Allergic reactions, such as excessive sneezing, are stimulated by the activation of this chemical, according to Medicine Net, because it "dilates blood vessels and makes the vessel walls abnormally permeable".
Low histamine is also known as histapenic. According to Naturopathic Care, it is characterised by excessive copper accumulations within the body and, when combined with the lack of histamine, "may produce behavioural abnormalities." Naturopathic Care lists both mental and physical symptoms which include ideas of grandeur, undue suspicion of people, the ability to stand pain well and heavy growth of body hair.
A high histamine level is also known as histadelia. Naturopathic Care states that this type tends to be genetic and causes "allergic reactions, increased production of mucus and saliva, a tendency to hyperactivity, compulsive behaviour and depression." Naturopathic Care lists both mental and physical symptoms for a high histamine imbalance which include regular and seasonal allergies, inner tension, abnormal fears/compulsions/rituals, heightened metabolism, and frequent aches and pains.