Fibromyalgia is a disorder characterised by widespread pain and heightened response to pain. This is accompanied by lack of sleep, fatigue, memory and mood related problems, sensitivity to light, noise or temperature.
It has also been associated with anxiety, depression and post traumatic stress disorder.
The exact cause is not yet known. Some individuals are genetically predisposed to developing fibromyalgia. Other external factors include infections, physical or emotional trauma.
Scientifically it is said that repeated nerve stimulation could impair the brain’s ability to process pain in fibromyalgia.
There is supposedly an increase in brain chemicals that lead to pain sensitivity. Also the brain’s pain receptors become sensitive to pain.
Females are more likely to develop fibromyalgia and the presence of rheumatic disease increases the risk of developing fibromyalgia.
Painkillers such as acetoaminophen and ibuprofen are prescribed. Opiod painkillers may be prescribed but are generally not advised. Antidepressants help in relieving pain and fatigue.
Certain anti-epileptic medications like pregabalin are used to treat fibromyalgia. Regular exercising, healthy diet and alternative therapies are also recommended.
What is capsaicin?
Capsaicin is the compound that offers hot and spicy flavour to chillies. Capsaicin and related compounds are called capsaicinoids and these are present in all the plants of genus Capsicum except for bell pepper which does not contain any capsaicin.
Capsaicin and dihydrocapsaicin are the major capsaicinoids. The naturally occurring content of capsaicinoids in spices ranges typically from 0.1 mg/g in chilli pepper to 2.5 mg/g in red pepper and 60 mg/g in oleoresin red pepper.
The Scoville Heat Unit Scale is used to classify the strength of chilli peppers.
Average intake of capsicum spices is 2.5g/person in India and upto 20g/person in Mexico. Capsaicin improves digestion and hence is used to fight diarrhea and stomach infection. It is also identified as a fat burner and can control appetite.
Research suggests that it may have implications on cancer, cardiovascular health and respiratory system.
However its prime use is for pain relief. Topical capsaicin is used for treatment of diabetic neuropathy, post surgical pain, cluster headaches, arthritis and psoriasis.
How does capsaicin help relieve pain?
Transient Receptor Potential Channels are important family of ion channels. Ion channels are a type of protein that serve as a gate and control the ions entering the cells. There are six subfamilies under TRP and they are activated in response to hot or cold stimulus.
The Transient Receptor Potential Vanillod 1 receptor (TRPV1) belongs to this family and is activated in response to capsaicin, heat, inflammatory mediators etc. TRPV1 has different functions based on its location.
It is located at the end of nerve fibres and is responsible for detection of pain, heat and chemicals.
Earlier it was thought that capsaicin brings about depletion of substance P, a brain related chemical involved in pain sensation, from the affected nerve fibres and this leads to pain relief.
However this no longer considered to be the case now.
Capsaicin is a member of vanilloid family of compounds such as vanillin from vanilla, eugenol from cloves etc.
Capsaicin binds to TRPV1 and brings about a similar reaction in the brain as that caused by heat. Therefore initially when you apply capsaicin based cream you experience warmth, itching and burning sensation.
On long term or on repeated application capsaicin leads to loss of function of the nerve receptors and leads to impaired sensation of pain.
Higher concentrations of topical capsaicin bring about neurolysis or temporary damage of nerve fibre which reduces pain sensation and nerve function is restored on cessation of capsaicin used.
Are there any studies that prove capsaicin helps in fibromyalgia?
De Silva et. al have identified capsaicin as a complementary/alternative medicine beneficial in treatment of fibromyalgia.
Two clinical trials have investigated the role of capsaicin in fibromyalgia while a quite a few studies point out that capsaicin help in relieving pain.
1. Capsaicin benefits in fibromyalgia
A 4 week study was conducted wherein 45 patients received either 0.025% capasaicin cream or placebo cream. They were asked to apply this cream 4 times daily. At week 4 capsaicin treated patients experienced reduction in tenderness.
An increase in grip strength was also observed in capsaicin treated patients. Researchers concluded that capsaicin cream can be an effective treatment for pain in fibromyalgia.
In another study, the effect of capsaicin cream on fibromyalgia related pain and overall emotional well being was observed. Topical 0.075% Capsaicin cream was used.
60 individuals continued medical treatment while 70 individuals continued medical treatment in combination with application of capsaicin cream (3 times daily for 6 weeks).
Improvement in myalgic score and overall well being was observed in capsaicin group. Significant reduction in depression and fatigue, role limitation due to emotional problems and improvement in pressure pain threshold was observed.
2. Capsaicin is beneficial for musculoskeletal pain
Keitel et. al studied the effect of capsaicin plaster on non specific chronic low back ache. After 3 weeks of treatment the response rate was 60.8% in capsaicin group compared to 42.1% in placebo group.
Response was measured as a 30% reduction in pain compared to baseline.
Mathias et. al have reported relief from chronic neck pain after applying 0.025% capsaicin cream four times a day for 5 weeks. 0.05% capsaicin cream is found to be beneficial in treating soft tissue pain in 3 weeks.
3. It can attenuate neuropathic pain
Neuropathic pain is a form of pain occurring due to damaged nerve fibres and is a symptom of fibromyalgia. High dose topical capsaicin preparations hold promisefor chronic neuropathic pain.
8% patch capsaicin has capsaicin concentration 100 times greater than conventional creams.
The mechanism of action of these patches was earlier attributed to depletion of substance P which was held responsible for pain sensation.
However it is found that capsaicin reduces hypersensitivity of the skin to pain and leads to ‘defunctionalisation’ of nerve fibres. These are temporary changes in the endings of nerve fibres which leads to reduced pain sensitivity.
A review study reports that these patches bring about an average 30-50% reduction in neuropathic pain when used for about 12 weeks. Improvement in quality of life, depression, fatigue and sleep was also reported.
Pregabalin is FDA approved medication for treating fibromyalgia. A study was conducted to compare the effect of 8% capsaicin patch with oral dose of pregabalin on neuropathic pain.
Within 8 weeks capsaicin patch was found to be as effective as pregabalin in bringing about 30% reduction in pain score. Time to onset of pain relief was shorter with capsaicin treatment and treatment satisfaction was greater with capsaicin. Also fewer side effects were reported.
Usage
Capsaicin is available as capsules and creams for external use. Oral consumption of capsaicin is not found to be beneficial for pain relief.
Capsaicin is commercially available as 0.025%, 0.075%, and 0.1% creams. These can be applied 3-4 times a day.
A single-application high-dose capsaicin 8% patch is available. This patch is generally applied by a medical practitioner and can be applied as frequently as every 3 months.
Initial burning and stinging sensation is possible that fades away and progressively reduces with repeated applications.
Precaution
Allergic reactions are possible with capsaicin. Therefore please do a patch test before using capsaicin topical cream. Do not apply capsaicin to broken skin.
It is advisable not use capsaicin for children. After using capsaicin wash your hands thoroughly and avoid touching eyes. Capsaicin does not wash off with water; you can use vinegar to wash it off.
Inhalation of capsaicin can cause respiratory irritation, sneezing, and tearing.
Capsaicin supplements should be avoided in pregnancy and breastfeeding. Capsaicin capsules can cause stomach irritation and should be avoided if suffering from heartburn or ulcers.
Capsaicin supplements could have drug interactions with blood pressure medications, blood thinning medications, diabetes medications and stomach acid reducing agents.
Conclusion
Capsaicin finds its use in pain management by interacting with nerve fibres and proteins that are involved in pain sensation. Topical formulation of capsaicin 0.025- 0.075% is effective in managing fibromyalgia related pain.
Reduction in pain leads to improvement in sleep and emotional well being.
Before using capsaicin cream please do a patch test. Use capsaicin cream with caution as it causes burning and stinging sensation especially if in contact with broken skin or eyes.
Capsaicin is a relatively inexpensive treatment for pain management.