By ROBERT J. DAVIS
Special to THE WALL STREET JOURNAL
March 29, 2005; Page D3

Recent news about the possible dangers of pain medications has prompted many to turn elsewhere for relief. Studies -- including one to be released this week -- suggest that heat wraps may be even more effective than over-the-counter drugs at reducing minor aches and pains. There are a number of wraps and patches that work in various ways, but choosing one that's both convenient and inexpensive can be a challenge.

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Researchers say heat affects certain nerve endings, which send signals to help block the sensation of pain. It also relaxes muscles and increases blood flow. The old standby method for delivering heat, electric heating pads, can have major drawbacks: You can't move around while using them, and they can cause burns, fires and electric shocks.

Manufacturers have come up with alternatives, including reusable wraps that are heated in the microwave. They typically contain gel or beads that produce warmth for 30 to 60 minutes. In many cases, it's a moist heat, which some doctors say is a more effective pain reliever than other types of heat. Many gel products can also be frozen and used as ice therapy for reducing swelling after an acute injury such as a sprained ankle.

You can also find disposable patches that contain ingredients such as capsaicin (a compound in hot peppers) or menthol, which don't actually heat the skin but create a sense of warmth. The products, which adhere to the skin or clothing, last for eight hours or longer.

Other disposable eight-hour products contain iron, which produces continuous, low-level heat when exposed to air. One such brand, ThermaCare made by Procter & Gamble, is the most extensively researched wrap. Several randomized, published studies, funded by the manufacturer, have shown the products can relieve low back pain more than ibuprofen or acetaminophen and also reduce menstrual pain. And a study to be presented this week at a meeting of the American Pain Society shows similar effectiveness for osteoarthritis of the knee. However, all the research is short-term, so the products' effects after months or years of use are unknown.

While disposable products are more convenient, they can be pricey -- as much as $3.50 apiece. For people with chronic pain who need to use a wrap every day, that can add up to more than $1,000 a year.

Heat should not be used on an injury if there's bruising or swelling. And people with diabetes or poor circulation, who may have decreased sensation and therefore greater susceptibility to burns, should first talk to their doctors, as should those who have rheumatoid arthritis or are pregnant.

Keep in mind that the pain-relieving effects may continue after you remove a long-lasting wrap, so you don't need to wear one continuously. If the product doesn't help after a week or so, see a doctor.

---- With reporting by Debra Goldschmidt

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