Effects of Histamine Release
Histamine is the chemical in the body that causes allergic reactions. According to FamilyDoctor.org, when someone encounters an allergen, the body releases IgE antibodies to fight off the substance. This release causes a chain reaction in the body that causes the mast cells to over-produce histamine. Increased histamine causes irritation and inflammation in various parts of the body. The most common places histamine causes a reaction is in the skin, the nasal passages and the bronchial tubes. Talk with a doctor about any allergy-related symptoms for the most effective treatment options.
The most common condition in the upper-respiratory system affected by histamine release is called allergic rhinitis. This allergy condition primarily focuses on the sinuses and the eye's reaction to increased histamine, according to the University of Maryland's Medical Center. Common symptoms include nasal congestion, a runny nose, sneezing and sinus pressure pain. Post nasal drip is associated with allergic rhinitis, especially when the nostrils are obstructed. Other symptoms in the upper-respiratory tract are irritation in the eyes and throat irritation. The eyes become red, swollen, watery and very itchy. The throat feels scratchy and can become sore from post nasal drip.
The release of histamine can cause skin rashes throughout the body, according to the American Academy of Dermatology. This type of reaction causes symptoms such as redness, inflammation and severe itching on the skin. The skin can develop welts or small blisters that can burst, making the skin more susceptible to infections, such as impetigo. The most common skin reactions caused by increased histamine levels are eczema, hives and contact dermatitis. Avoid scratching the skin, wear loose fitting clothing, and stay away from hot and humid conditions. Talk with a doctor if skin symptoms do not improve within a 24-hour period.
Asthmatic symptoms due to the release of histamine are referred to as allergy-induced asthma, according to the Asthma and Allergy Foundation of America. Allergy-induced accounts for 50 percent of asthma condition in the United States. When the body releases histamine, it causes the bronchial tubes to become inflamed and swollen. This leads to restricted breathing and wheezing. The person may feel tightness in the chest and will not be able to take a deep breathe. She may feel faint or develop anxiety because of the lack of air. Asthma can lead to a life-threatening situation and needs to be evaluated by a physician.
Excess histamine release causes inflammation and allergy. They are chemicals released by specialized cells, called mast cells, as a defense mechanism. Mast cells also play a role in immunity. Histamines have an inflammatory effect on the body.
Itching and Pain
Excess histamine release causes itching and can also cause pain. Two types of histamine receptors that are known to cause specific effects are present in the body are H1 and H2. Itching is caused by activation and release of H1 receptors when the body is exposed to foreign substances that induce an allergic reaction. Because histamine (H1) receptors are abundant in the skin, exposure to an allergen causes their release, producing itching and pain from stimulation of sensory nerve endings. An example is itching, swelling and pain that occurs in response to an insect bite.
Swelling is an effect of excess histamine release and happens when blood and fluid escape from the capillaries and leak into extracellular spaces. Blood vessels dilate and collapse, causing blood to become trapped and contributing to swelling, also known as edema. Anaphylactic shock is a severe type of allergic reaction that results from excessive release of histamine. Swelling in the throat, around the eyes, and lips, and wheezing and difficulty breathing are hallmark symptoms of anaphylaxis. The effect of histamine release on the lungs can lead to pulmonary edema, fluid that collects in the respiratory air sacs, from leakage of fluid through the veins in the lungs (pulmonary veins). The same mechanism is what causes runny nose, itchy eyes and sneezing in response to a cold virus or allergen.
Increased Gastric Secretions
Specialized cells in the stomach, called parietal cells, secrete hydrochloric acid. Too much hydrochloric acid leads to ulcers and inflammation. Mast cells are also present in the lining of the stomach that release histamine and contain H2 receptors. Histamine has an effect on parietal cells, combined with other enzymes, that leads to increased gastric secretions.
Sleep and Wakefulness
Histamine affects brain chemicals that regulate sleep and wakefulness. They act as neurotransmitters in the brain. Neurons in the brain that transmit signals contain histamine that increase when we are awake. The effect of histamine on wakefulness explains why antihistamine medications make us sleepy.