Histamine intolerance can cause the body to react in a wide variety of ways. In almost all cases, the symptoms occur because the body's ability to break down or lower levels of histamine has been compromised; once levels of histamine reach a certain trigger point, this chemical excess can produce a wide range of problems and symptoms.

Among the most common symptoms of histamine intolerance are skin and cardiovascular issues. These can include nasty rashes and swellings such as hives, arrhythmia, problems with the regulation of body temperature (which can cause sweats or chills), or hypertension.

Other very common symptoms include headaches - often severe enough to trigger migraines - vertigo and dizziness, and problems sleeping. Other signs of intolerance can include nausea or vomiting, bouts of anxiety, the onset of flu-like symptoms such as sneezing and watery eyes, abdominal pain, and swollen tissue, especially around the mouth, eyes or throat.

Where the intolerance especially manifests in the digestive tract, symptoms may often include diarrhea, irritable bowel syndrome, severe constipation, a feeling of being overly full, nausea and vomiting. These can also be linked to a range of other causes and conditions, so often relatively simple histamine intolerance can be overlooked.

Females may experience a range of additional issues caused by too much histamine in the system. These can include really severe period pains, known as dysmenorrhea, low blood pressure, and swollen joints. When a woman is pregnant, the placenta releases large quantities of diamine oxidase (DAO), an enzyme which naturally lowers histamine levels. This can therefore temporarily relieve the symptoms and root cause of many histamine-influenced issues, but after birth these symptoms may well return once levels of DAO have dropped off.

Individuals who suffer from skin problems such as eczema may well find that histamine tolerance exacerbates the condition and worsens symptoms. This can particularly occur following the consumption of foods rich in histamines or which release histamine readily - excessive itching and rashes may present, and cause much greater suffering.

Histamine intolerance is thus linked to a wide variety of symptoms, and certainly not every individual will experience all of them; some may only be affected in one or two ways. However, the intolerance will present itself in a repeated way and thus become easier to identify over time.