Capsaicin (also known as cayenne, cayenne pepper, chili pepper, and Goat’s Pod) is the compound that gives hot peppers their “heat” or spiciness. Capsaicin is commonly used to relieve pain associated with a variety of conditions, and researchers believe that it does so by affecting the communication of pain signals between the spinal cord and the rest of the body. Capsaicin is available as a powder that can be mixed with food or drinks, as an oral supplement, and as an ingredient in topical creams for use on the skin.
When used on the skin, it may be useful to help relieve pain following surgery, pain due to various nervous system disorders, cluster headaches, osteoarthritis, rheumatoid arthritis, psoriasis (a skin condition characterized by red, itchy, scaly patches), and mouth sores that result from chemotherapy or radiation therapy. When capsaicin is taken as a dietary supplement, it may help to improve digestion, fight infection, and relieve diarrhea. In addition, capsaicin may help to prevent heart disease by lowering cholesterol levels and blood pressure, as well as preventing blood clots.
Capsaicin is generally safe when used appropriately, however it can cause side effects. Capsaicin may cause a burning or painful sensation when it is first used, but such side effects generally improve with use over time. Allergic reactions are possible, therefore those who are just beginning to use capsaicin should start with small amounts. In addition, topical creams should be tested on a small area of unbroken skin first to ensure that no adverse reactions occur. Capsaicin should not be used by anyone who has high blood pressure or who is being treated for high blood pressure. Also, excessive intake of capsaicin may cause ulcers on rare occasions. Avoid contact with the eyes and other mucus membranes, and do not apply capsaicin-containing creams to broken skin.
Capsaicin and Fibromyalgia
One study has evaluated the use of capsaicin to treat fibromyalgia tender point pain. A randomized controlled trial compared the effectiveness of a skin cream containing 0.025% capsaicin (Zostrix®) versus a placebo in 45 fibromyalgia patients. The participants were randomly assigned to one of four groups: 1) Zostrix® applied to right side tender points; left side tender points served as controls; 2) placebo cream applied to right side tender points; left side tender points served as controls; 3) right side tender points served as controls; Zostrix® applied to left side tender points; and 4) right side tender points served as controls; placebo cream applied to left side tender points. Patients were assessed for pain, tenderness, and quality of sleep both at the beginning of the study and following four weeks of treatment. The researchers found that those treated with capsaicin experienced significant improvements in tenderness, but no improvements in pain or quality of sleep. Adverse events included stinging and burning at the application sites, which is characteristic of topical creams containing capsaicin (McCarty et al., 1994).
Capsaicin and Pain Relief
Despite the lack of research related to capsaicin and fibromyalgia, capsaicin may still prove useful to many fibromyalgia patients due to its demonstrated properties to improve pain associated with a number of other conditions. Mason et al. (2004) reviewed 16 published studies, encompassing data from 1,556 patients, all of which compared the use of capsaicin-containing skin creams to placebo or other treatments. Overall, the pooled analysis showed that capsaicin was significantly better than placebo at treating both neuropathic (nerve) and musculoskeletal pain. For patients with neuropathic pain, on average, 57% of those treated with capsaicin experienced at least a 50% reduction in pain after four weeks of treatment, versus only 42% of those treated with placebo. Among the musculoskeletal pain patients, 38% experienced at least a 50% reduction in pain after four weeks of treatment versus 25% in the placebo groups. However, when compared to placebo, capsaicin produced significantly more side effects in all studies and contributed to more patients withdrawing from studies due to adverse events (Mason et al., 2004).
More recent research also supports these findings. Chrubasik et al. (2010) studied 281 patients with chronic soft tissue pain in a randomized, double-blind, placebo-controlled study (the “gold standard” for research studies that attempt to evaluate the effectiveness of a particular treatment). In this study, 140 patients were randomly assigned to receive treatment with a 0.05% capsaicin-containing cream (Finalgon® CPDWärmecreme) while another 141 were randomly assigned to receive a placebo cream. Data from 126 patients met criteria for analysis at the end of the study. At the end of a three week course of treatment, those in the capsaicin group experienced a median decrease in pain of 49%, versus 23% for the placebo group. Similar to other studies, however, more individuals in the capsaicin group experienced side effects (13 patients versus six in the placebo group) (Chrubasik et al., 2010).
Research has also shown that nasal sprays containing capsaicin can be beneficial to some patients who experience both cluster headaches and migraine, which are both common among fibromyalgia patients. Often, these sprays are most effective when sprayed into the nostril located on the side of the head in which the headache is most prevalent (Fusco et al., 1994). However, studies have also shown that patients tend to prefer oral capsaicin tablets to nasal sprays, as many capsaicin nasal formulations can be painful when administered. In addition, nasal sprays may not be as well-absorbed as oral supplements and therefore not produce consistent benefit (Rapoport et al., 2004). Despite these potential drawbacks, capsaicin-containing nasal sprays can serve as an added therapeutic option to many and may result in faster pain relief when compared to oral capsaicin products.