The appearance of red welts on your skin after taking acidophilus supplements can be frightening. Hives is a common symptom of an allergic reaction after taking acidophilus, according to Drugs.com. The rash, itchiness and inflammation from hives are harmless, but they might be a sign of anaphylaxis, a severe allergic reaction that could lead to life-threatening complications. Any time you develop a rash from taking a supplement, talk with your doctor.
Acidophilus
Acidophilus is a strand of a category of microorganism called probiotics. Probiotics are helpful bacteria that are commonly found in the human digestive system that help maintain a balance between good and harmful bacteria. Acidophilus is commonly used to prevent and treat vaginal yeast infections and diarrhea, as well as to maintain normal bowel movements. If you have artificial heart valves, a compromised immune system disorder or a milk allergy, you should avoid using this supplement, according to MayoClinic.com. Acidophilus supplements are not regulated by the Food and Drug Administration and should be used under a doctor's supervision.
Allergic Reaction
Drugs.com states that the development of hives is a sign of an allergic reaction to acidophilus. Hives are a sign that your immune system is overreacting to the presence of the probiotic supplement. Instead of the immune system identifying the substance as safe, it mistakes it for an intruder that can hurt the body. This mistake triggers a chemical chain-reaction that causes the production of immunoglobulin E antibodies, according to the American Academy of Allergy, Asthma and Immunology. When IgE antibodies enter the blood stream, they alert mast cells that the body is under attack. The mast cells produce histamine, which causes blood vessels to dilate and become inflamed.
Hives
The presence of histamine can cause blood vessels in the surface of your skin to dilate, resulting in the formation of hives. Hives can appear anywhere on the body and cover a small to large surface area. The rash is very itchy and causes inflammation in the skin that produces welts with a flat surface and defined borders. Hives are circular in shape but can develop in various sizes and commonly migrate together to form a larger welt. Hives are not dangerous, unless they develop in your throat, affecting your breathing.
Warning
Hives that develop with shortness of breath, facial, tongue, throat, or lip swelling may be a sign of anaphylaxis. During anaphylaxis, excessive amounts of allergy-fighting chemicals overwhelm the body, sending the body into a state of shock. This can lead to death if not treated with an injection of epinephrine.
