Allergies are one of the most common chronic conditions in the world—in the U.S., as many as 50 million people have them. Many people regularly take antihistamine medications to relieve allergy symptoms that may include itching, skin rashes, runny nose and wheezing.

Antihistamines block the effects of histamine, which is a very strong and abundant biological substance. When the body is not in danger, histamine is stored in “bubbles,” or granules, in special immune cells. As soon as your body recognizes an unfavorable situation—for example, if we were scratched by our beloved cat or inhaled something that we’re allergic to, such as pollen or dust—histamine is quickly released from these bubbles. After its release, the main task of histamine is to help expel the “danger” from the body, which is why we begin to scratch the injury site or start to cough. Histamine can cause smooth muscle contractions in the lungs and stomach, increasing the amount of mucus or gastric secretions you produce and dilating small blood vessels. All these responses are geared toward getting rid of an allergen. Antihistamines help calm these responses.

A survey published in 2021 reported that half of all adults with an allergy take antihistamine pills. Many of us are very accustomed to using these drugs to treat allergy symptoms. However, most of us don’t know that histamine plays a role beyond the allergic response. Our kidneys, for example, have the machinery needed to make their own histamine. Research shows that histamine levels increase in kidney disease. Histamine helps control the amount of salt and water in the urine, which affects our blood pressure, but overall, very little known is known about how histamine affects kidney function. New research in mice suggests that activating certain components of the histamine response may protect against heart and kidney damage. 

These findings open new avenues of research for diseases that are not typically studied in relation to histamine. Can we use existing histamine-related medications to treat kidney disease? Do people with chronic kidney disease need to be careful when using antihistamines? Scientists have yet to answer these questions, but hopefully in time, more research will lead to new treatments.

Aleksandra Zamaro, MD, is postdoctoral fellow in the Department of Physiology in the lab of Daria Ilatovskaya, PhD, at Augusta University. Zamaro’s research focuses on renal physiology, particularly the role of mitochondrial bioenergetics and histaminergic system in hypertension.