CREAMS AND TOPICALS
There are many different topical creams and jells that are available on the market today to help provide temporary relief of pain. The majority of these creams and jells work on the basis of counter irritation. (That is they work by causing one sensation that results in reduction of pain awareness.) When they are applied to an area, such as over a painful joint, they produce a temporary local reaction causing skin irritation and might also result in mild swelling or temperature increase because of increased blood flow. These changes cause stimulation of certain nerves which can "cover up" pain. One can look at it based on the "gate theory" of pain which simply stated proposes that there are only a certain number of nerve channels from any given area of the body to the brain that serve as conduits for sensory information, including pain. If we fill up enough of those conduit channels with non-painful stimuli, we inhibit the ability of the pain signals to get through to the brain and to be perceived. In this case, we are not really changing the painful condition, we are, however, changing the experience so that we are more aware of other sensations than the pain and therefore we are more comfortable.
Most counter irritant topical creams or jells use heat or cold to "gate" the pain or cover it up, thus reducing the experience of pain.
Some creams contain acetylsalicylic acid (aspirin) which can be absorbed to some extent though the skin. Aspirin, of course, has analgesic (pain relief) and anti-inflammatory effects. One should understand when using creams with acetylsalicylic acid that this needs to be taken into account when considering the daily dose of acetylsalicylic acid or Motrin (Ibuprofen) taken orally. It is not easy to calculate how much aspirin is absorbed with topical applications.
Another type of topical cream used for the treatment of localized pain contains a compound contained in hot chili peppers called capsaicin. Capsaicin is the alkaloid that really gives chili peppers their hot spicy flavor. This, too, tends to be a counter irritant. These preparations are available without prescription with names such as Capsin, Capzasin-P and Zostrix. Most contain up to one quarter percent of capsaicin. When used they do tend to cause a feeling of warmth and they can be applied several times per day.
Capsaicin appears to have more affect than just as a counter irritant, however. Research has shown that Capsaicin, in fact, affects a molecule known as Substance P. Substance P is a neurotransmitter important in transmission of pain impulses through nerves. Capsaicin appears to reduce the production and secretion of substance P, thus inhibiting the nerve cells ability to transmit pain impulses.
In 1995, the University of California at Berkley Wellness Letter indicated that Capsaicin has been found beneficial for reducing pain in many people. Generally, the cream is applied topically, by rubbing it into the skin three or four times a day. Pain relief, however, may not occur right away and in some people only occurred after the cream had been used for several days or more. Unfortunately, there are some people who just cannot tolerate this cream and if skin irritation occurs that does not resolve rapidly, it is recommended to stop using the cream. In addition, it should never be used with an occlusive dressing over the cream, never in open wounds or, in one's eyes.
There are other creams and ointments that have been at least anecdotally effective in the relief of pain, and may be worth trying in some cases if they have proven to be harmless.