Q: Which over-the-counter pain-reliever is safest: acetaminophen, ibuprofen, naproxen or ketoprofen?

A: All these drugs are considered safe for short-term use (up to 10 days) in most people. That's why they got the OTC nod.

However, there are certain risks we'll take a look at.

Ibuprofen, naproxen, and ketoprofen belong to the drug family called NSAIDs. They work against pain, fever and inflammation.

Acetaminophen works against pain and fever, but not inflammation. Products include Tylenol and various generic and store brands.

The NSAID products include ibuprofen (Advil, Motrin IB, Midol IB, Nuprin), naproxen (Aleve) and ketoprofen (Actron, Orudis KT). Various generics and store brands also are available.

Acetaminophen has a long safety record when used in recommended doses. However, excessive doses can damage the liver. People at highest risk are those with liver disease, heavy alcohol users, and fasting or malnourished individuals.

Adults should stay well below the ceiling dose of 4,000 mg in any 24-hour period. That's equivalent to eight extra-strength Tylenol pills (500-mg each).

Acetaminophen use in children warrants extra caution. Over 25,000 accidental overdoses are reported annually.

Follow label directions carefully on products for kids. Use only the dropper or dosing device provided with the product. Give the recommended dose and don't go over the total number of recommended daily doses.

Various multi-ingredient products contain acetaminophen, including many cold and cough products. Include these when figuring the total daily amount of acetaminophen given.

Symptoms of liver damage include unexplained nausea and vomiting, abdominal pain/pain in right chest, fatigue, appetite loss, dark urine and yellow skin or eyes (jaundice).

Now to NSAIDs. Safety concerns with these drugs primarily relate to long-term use and higher doses.

NSAIDs carry both gastrointestinal and cardiovascular risks.

Potential GI risks include bleeding, ulceration, and perforation of the stomach or intestines. These effects can be insidious - they may occur without warning symptoms.

GI risk is highest in the elderly, debilitated, moderate alcohol drinkers, those who take a blood thinner such as warfarin (Coumadin), and those with a history of stomach or duodenal ulcers or bleeding.

Potential cardiovascular risks include heart attack and stroke. People most at risk are the elderly and those with kidney impairment, high blood pressure, fluid retention or congestive heart failure.

Those who take a daily low-dose aspirin for cardiovascular protection should be aware that OTC NSAIDs might interfere with aspirin's blood-thinning action.

Ibuprofen (and possibly other NSAIDs) appear to block aspirin from reaching its receptors.

Timing is important. Taking aspirin two hours before an NSAID appears to solve the problem. That gives aspirin time to claim its space before NSAID interference. (This may not work when an NSAID is taken multiple times daily.)

Serious adverse effects with OTC pain relievers are rare when they're taken according to label directions.

Those at higher risk, as listed above, should check with their clinician before using these products.

(Richard Harkness is a consultant pharmacist, natural medicines specialist and author of eight published books. Write him at 1224 King Henry Drive, Ocean Springs, MS 39564 or rharkn@aol.com.)