From the Guidelines
Hives themselves do not directly increase blood pressure, but severe allergic reactions like anaphylaxis can lead to a dangerous drop in blood pressure. According to the 2020 practice parameter update on anaphylaxis by the Journal of Allergy and Clinical Immunology 1, anaphylaxis is characterized by acute onset of illness with involvement of the skin, mucosal tissue, or both, with either respiratory involvement or reduced blood pressure and/or associated symptoms of end-organ dysfunction. The key points to consider are:
- Hives are a common symptom of allergic reactions, but they do not typically affect blood pressure directly.
- Severe allergic reactions, such as anaphylaxis, can cause a drop in blood pressure, which is a life-threatening condition.
- The discomfort, pain, and stress associated with hives might temporarily raise blood pressure in some individuals as a secondary response to distress.
- Treatments like antihistamines can help manage symptoms of hives without affecting blood pressure significantly.
- If hives occur with symptoms like difficulty breathing, dizziness, or swelling of the face or throat, seek emergency medical attention immediately as these could indicate anaphylaxis, which requires immediate treatment with epinephrine, as suggested by the NIAID/FAAN criteria 1.
From the Research
Hives and Blood Pressure
- The relationship between hives and blood pressure is not directly addressed in the provided studies 2, 3, 4, 5, 6.
- However, it is known that hives (urticaria) are caused by the release of histamine and other inflammatory mediators from mast cells and basophils, which can lead to increased blood flow and permeability of blood vessels 2.
- Anaphylaxis, a severe and life-threatening allergic reaction, can cause a rapid drop in blood pressure, but this is not directly related to hives 4.
- The treatment of urticaria typically involves the use of antihistamines, which can help to alleviate symptoms such as itching and swelling, but their effect on blood pressure is not explicitly stated in the studies 3, 5, 6.
- It is worth noting that some antihistamines, particularly first-generation antihistamines, can have sedative and anticholinergic effects, which may indirectly affect blood pressure, but this is not a direct consequence of hives 5.