Aspirin is also commonly used to bring down a fever. Do not use aspirin for a fever in children or teenagers if their fever is from a cold, flu or any other virus, like chicken pox. A very serious illness called Reye's Syndrome can occur. Aspirin is also used to thin the blood. Persons who have had a stroke or heart attack sometimes need to have their blood thinned so that blood clots do not form.
Blood clots are clumps of blood cells that can block the normal flow of blood.
Stomach upset and gastrointestinal bleeding are side effects that can happen to persons taking aspirin. It is very important to notify a healthcare provider if they occur. Try to take aspirin with food and a glass of water. Aspirin is available with a coating to protect your stomach, but it should never be held in the mouth for a long period of time. Aspirin can cause trouble breathing, itching, or other allergy symptoms in some people.