Prescription drugs require a doctor or other health care provider to monitor their effects.

Aspirin and other salicylates can bring on severe asthmatic attacks in sensitive people, according to the American Academy of Family Physicians. People with nasal polyps also may experience breathing problems. Others at risk are those who have high blood pressure. Children shouldn't be given aspirin because of its link to Reye's syndrome, a potentially fatal illness.

Allergic reactions may include a rash, itching and breathing difficulties.

Keep track of how many consecutive days you take aspirin, ibuprofen, naproxin or acetaminophen, the FDA says. If you're still having problems after seven to 10 days, see your doctor.

If you take more than an occasional dose of acetaminophen, don't drink. Overdoses of acetaminophen alone are toxic to the liver. Alcohol in combination with recommended dosages of acetaminophen may be toxic to the liver.

Antacids can increase or decrease the rate and/or extent of absorption. Another danger with taking antacids for extended periods without a diagnosis is that they may mask a more serious problem, such as an ulcer or esophageal cancer.

These drugs block histamine receptor sites. A side effect of antihistamines is the blocking of a chemical neurotransmitter called acetylcholine. Because the elderly produce less acetylcholine and can't use it as well, they may experience pronounced side effects, such as confusion, a dry mouth, lightheadedness and problems with urination, the FDA says.

These spoons resemble wide straws with a spoon at one end. They are designed for children who can drink from a cup but are likely to spill. Measure the dose at eye level.

Multi-symptom medications expose you to drugs you don't need, which increases the risk of side effects.