Aspirin, ibuprofen and other nonsteroidal anti-inflammatory drugs (NSAIDs) may cause an upset stomach in some people. This effect tends to be more pronounced in people who take aspirin but may occur with any of these medications. Acetaminophen is less likely to cause upset stomach and may be a good alternative for some people.

Taking aspirin or ibuprofen with a full glass of water or milk may also help reduce stomach upset. In addition, certain medications (e.g., buffered aspirin) may be coated with an antacid designed to reduce stomach upset. However, if patients suffer from gastrointestinal ulcers all these medications with the exception of acetaminophen should generally be avoided.

Other side effects associated with certain headache medications include:

• Allergic reaction or increased risk of asthma attack
• Bloody or black stools
• Constipation, diarrhea or gas
• Dizziness
• Drowsiness
• Headache
• Increased risk of bleeding and other blood problems
• Mental confusion
• Ringing in the ears (tinnitus) or hearing loss
• Skin rash
• Stomach pain, cramps and vomiting
• Wheezing or other breathing difficulties

In 2005, the U.S. Food and Drug Administration (FDA) announced that it was asking manufacturers of NSAIDs to include new warnings on their labeling about certain potential health dangers associated with these medications, such as an increased risk of cardiovascular events. Patients concerned about these risks should consult their physician about the risks and benefits of taking NSAIDs. 

People who take too much of a medication may find that doing so worsens the severity or frequency of headaches. These are known as rebound headaches. For this reason, it is critical that patients take these medications exactly as prescribed by a physician.