What to rub on sore muscles

My 64-year-old friend Mark loves riding his mountain bike every weekend. In the winter he heads to our local ski area, White Pass, where he “shreds” with his son, Chris. Last week, he asked me, “What can I use for sore knees that isn’t a pill?”

There are lots of products available without a prescription that Mark could apply directly to his skin to soothe sore muscles or aching knees. Natural compounds like wintergreen oil, camphor, menthol and capsaicin have been used for decades for muscle pain.

These plant-based compounds are called counterirritants. They stimulate the nerves in your skin, which blunts your pain sensation. When rubbed on sore muscles, they can create intense warmth, soothing coolness, or burning/tingling. Because they are not easily absorbed into your bloodstream, these topical agents can relieve discomfort with a much lower risk of side effects than pain pills.

Other options for Mark include lidocaine and diclofenac. These alternatives work very differently. Lidocaine is a local anesthetic, and diclofenac (Voltaren®) is an anti-inflammatory agent similar to naproxen (Aleve®) and ibuprofen (Motrin-IB®).

I recommend using a 4% lidocaine roll-on for nerve pain and diclofenac gel for arthritis pain. I avoid suggesting capsaicin because it causes burning and has to be reapplied 2-3 times daily to maintain relief.

Capsaicin is derived from chili peppers. It works by triggering a nerve messenger called Substance P to be released from the area you apply it to.

Substance P acts like a telephone line, carrying messages to your brain that you've got pain in your knee. Capsaicin releases even more Substance P, until it can’t send any more messages until it builds back up. For example, when you flush a toilet, the water must be replaced before you can use it again.

When applied for the first time, capsaicin causes a moderately intense burning and tingling sensation, the result of Substance P being released. This is followed by a diminished sensation of pain that persists for up to 8-10 hours.

Eventually, as your body replaces Substance P, you’ll feel tingling and burning start to come back. To maintain pain relief, you’ll need to reapply capsaicin.

Because capsaicin is made from hot chili peppers, wash your hands immediately after applying it. Touching your eye with capsaicin on your fingers feels just like throwing pepper in it. I recommend using a roll-on applicator for capsaicin to avoid touching the stuff. 

Many non-prescription topical analgesics contain at least one plant-based product, such as methyl salicylate (also called wintergreen oil), menthol, which is derived from peppermint oil, camphor, eucalyptus oil, turpentine, and an odorless cousin of methyl salicylate called trolamine salicylate.

Some of the more potent formulations Mark could select from include Aspercreme® Heat Pain Relieving Gel, with 10% Menthol; Tiger Balm® Arthritis Rub, which has 11% each of menthol and camphor; and Ben-Gay® Ultra Strength Pain Relieving Cream, containing 30% methyl salicylate, 10% menthol, and 4% camphor.

What if Mark prefers methyl salicylate products but wants to avoid smelling like wintergreen? He could switch to the odorless Aspercreme® formula containing trolamine salicylate instead of methyl salicylate.

Bayer, the manufacturer of Aleve®, has recently introduced two topical pain relief products: AleveX® as a lotion, spray and roll-on, and Aleve Arthritis Pain® gel. What's confusing is that neither one contains naproxen, the active ingredient in the brand name Aleve®.

This is an example of "brand extension," which is capitalizing on the name recognition of a trademark to market a different active ingredient. My husband finds this misleading and frustrating.

Instead of naproxen, AleveX® contains 16% menthol and 5.5% camphor, similar to Tiger Balm®. Aleve Arthritis Pain® gel contains diclofenac, the same ingredient found in Voltaren® gel.

Tylenol Precise Cooling® cream is another example of brand extension. Instead of acetaminophen, this cream contains both 4% lidocaine and 1% menthol.

Dr. Louise Achey, Doctor of Pharmacy, is a 44-year veteran of pharmacology and author of Why Dogs Can’t Eat Chocolate: How Medicines Work and How YOU Can Take Them Safely. Get clear answers to your medication questions at her website and blog, TheMedicationInsider.com.