In fact, to prevent accidental overdose, the maker of Extra-Strength Tylenol brand acetaminophen has reduced the maximum dose from eight pills (4,000 mg) to six pills (3,000 mg) a day.

Because the signs and symptoms of liver damage from acetaminophen may not be immediately noticeable, if you think you may have taken too much it is important to call 911 or poison control at 800-222-1222 right away.

You should not take acetaminophen if you have three or more alcoholic drinks daily or if you have advanced liver disease.

NSAIDs work similarly to aspirin to ease joint pain. Although there are more than a dozen NSAIDs available by prescription, only two are currently available OTC: ibuprofen (Advil, Motrin IB) and naproxen sodium (Aleve).

Ibuprofen is also available in many generic and store-brand products and, like acetaminophen, may be the active ingredient in products labeled "non-aspirin pain relief."

Use of NSAIDs can increase the risk of heart attack or stroke, particularly in higher doses. However, the most common side effects of NSAIDs are heartburn, indigestion, abdominal or stomach cramps, diarrhea, nausea, and vomiting. You can reduce the risk of side effects by taking the medicine with food or milk.

Other possible side effects include:

You should not use NSAIDs for pain if you are allergic to aspirin or similar drugs. If you have heart disease, kidney disease, liver cirrhosis, high blood pressure, asthma or a history of stomach problems, or if you take blood thinners or a diuretic, ask your doctor before taking NSAIDs. If you are pregnant or nursing, you should ask your doctor before taking naproxen, although ibuprofen is considered safe except during the third trimester of pregnancy.

Because many OTC products contain the same ingredients, it's important to know what’s in the medicines you take. Otherwise, if you take more than one product, you may get too much of one ingredient. Overdoses of any of these pain relievers can increase the risk of side effects and even be fatal.

Some products also combine ingredients. For example, aspirin may be combined with acetaminophen in a single tablet. Some medicines combine OTC pain relievers with other drugs, such as antihistamines, decongestants, or pain medicines to help you sleep.

There may be times when your doctor says it’s OK to use more than one drug -- such as when you have a cold or the flu. But you should not use more than one medication long-term for joint pain. If you need more than one drug, ask your doctor to prescribe them separately so you can get the appropriate dose of each.