Acetylsalicylic acid is aspirin, a commonly used pain reliever classified as a nonsteroidal anti-inflammatory drug, or NSAID. It is effective in relieving minor aches and pains, as well as reducing fever, and can also be used to prevent blood clots. More recently, aspirin has been recommended as a preventative for heart attacks and strokes, according to Drugs.com. Most people can safely use products containing acetylsalicylic acid, but side effects are possible, especially with overuse.
Gastrointestinal Distress
The most commonly reported side effects of acetylsalicylic acid involve gastrointestinal distress and abdominal discomfort, including nausea, cramping and abdominal pain, according to Drugs.com.
Ulcers
Using products containing aspirin can cause ulcers, especially when used frequently, according to the American College of Gastroenterology. The ulcers develop because acetylsalicylic acid irritates the stomach lining. In some cases, these ulcers may cause internal bleeding. Signs of internal bleeding include blood in the stool or black, tarry stools. However, in some people the bleeding may go unnoticed except for dizziness upon standing.
Liver Toxicity
Liver toxicity and damage to the liver are also possible side effects of acetylsalicylic acid, especially when large doses are taken over an extended period, according to Drugs.com.
Tinnitus
Tinnitus, or ringing in the ears, is another possible side effect of acetylsalicylic acid. In many cases, these effects can be reduced or eliminated by taking a smaller dose of the aspirin-containing product, according to Drugs.com. In addition to ringing in the ears, some people have also reported experiencing vertigo or dizziness.
Reye's Syndrome
Children with a fever who take products containing acetylsalicylic acid are at risk for developing Reye's syndrome, a serious and potentially life-threatening condition in which the liver and nervous system are damaged. Common signs of Reye's syndrome include vomiting, neurological impairment and liver damage, according to Drugs.com. Because of the risk of death, children with a fever should never be given products containing aspirin.
