04/03/2026
Histamine excess and allergies can often be a direct correlation of gut health which can be a down regulation of thyroid activity.
This includes food allergies
Histamine causes anxiety and panic attacks - usually alongside gastrointestinal issues and nasal congestion.
In some people, it is due to a deficiency of DAO - an enzyme that breaks down histamine.
“A 40-year-old woman presented with sneezing, postnasal drip, chest tightness, pruritus, fatigue, and palpitations. Alcohol triggered vomiting and hypotension. She also experienced bloating after eating shrimp and had softer stools.... A low-histamine diet and DAO supplementation significantly improved symptoms.”
“A 25-year-old woman presented with persistent postnasal drip, throat irritation, sneezing (triggered by sunlight), nasal discharge and congestion, occasional dyspnea, and frequent palpitations. She also reported gastrointestinal symptoms, including diarrhea after consuming fast food and chocolate.
She had gallbladder polyps, PCOS, and rosacea. During palpitations, her heart rate reached 140 beats per minute (bpm), and blood pressure was typically low (90/60 mmHg).. Anxiety was suspected. DAO level was 10.3 IU/mL. Upon starting a low-histamine diet and DAO supplementation, she experienced increased energy and decreased fatigue, sneezing, and palpitations.”
“A 54-year-old woman presented with nasal congestion, nausea, and palpitations that occasionally awoke her at night. Her heart rate sometimes reached 180 bpm, and blood pressure was consistently low. Panic attacks were previously diagnosed... A low-histamine diet and DAO supplementation led to improved allergic symptoms and near-resolution of palpitations.”
“A 26-year-old woman presented with clear nasal discharge, sneezing, mild cough, sputum, skin rashes on her arms, pruritus, and palpitations. Her heart rate occasionally reached 140 bpm at rest. She was diagnosed with anxiety. DAO level was 5.6 IU/mL. A 2-month course of low-histamine diet and DAO supplementation led to complete symptom resolution.”
PMID: 41211484
Hypothyriodism is another overlooked cause of high histamine:
Experimental hypothyroidism caused:
— 4.5x increase in mast cells
— 50% increase in histamine
— Increased degranulation
“In this study, we investigated the putative regulatory role of the pituitary–thyroid axis on mast cells (MCs). We found that hypothyroidism resulted in a significant increase in number of MCs and the histamine content in the skin and exorbital lacrimal gland of Wistar rats, Rattus norvegicus. Furthermore, an increase in the percentage of degranulating MCs suggests that the thyroid status also influences the activation state of these cells.” PMID: 35883387