Vitamins are intended to promote health, but they can give some people an upset stomach. Vitamin supplements are concentrations of essential vitamins you would typically acquire through food. Sometimes supplements can upset your stomach. This is often the case with multivitamin and mineral supplements that contain iron or zinc. Occasionally, however, an upset stomach can be the result of an allergic reaction or a food intolerance. If your gastric symptoms are severe or unusual, talk with your doctor.
Gastric Sensitivity
Some people have stomachs that are highly sensitive. Someone with gastric sensitivity may not be able to drink coffee or alcohol or eat spicy food without getting an upset stomach afterward. If you have gastric sensitivity, try eating before you take any supplement. The food will protect your stomach lining. If that doesn't solve the problem, talk with your doctor.
Allergic Reaction
On occasion, vitamin supplements can cause an allergic reaction. Most supplements are made with synthetic ingredients, which may be mistaken by your immune system as a harmful substance. If this mistake occurs, your immune system will create antibodies and histamine to fight off the allergen, according to the American Academy of Allergy, Asthma and Immunology. Common symptoms of an allergic reaction to a vitamin supplement include nausea, vomiting, diarrhea, hives, shortness of breath and nasal congestion. Nausea from an allergic reaction is usually accompanied by one or more allergy symptoms.
Food Intolerance
Vitamin supplements contain various inactive ingredients that are used to preserve, color and flavor the supplements. Intolerances are different from allergic reactions, because they are the result of a digestive complication and do not involve the immune system. For example, some supplements have milk byproducts, which could cause an episode of lactose intolerance, which is the inability to digest the sugar in milk. Other possible intolerances that could cause stomach upset include gluten and soy.
Considerations
If you experience similar symptoms after you eat certain foods, you may have a more serious digestive condition. Irritable bowel syndrome, peptic ulcers and Crohn's disease can all cause stomach sensitivity when you take vitamin supplements. Severe stomach pain and blood in your vomit or diarrhea are alarming symptoms that may require immediate medical attention.
