Capsaicin, which is often marketed as Capsagel, is a topical ointment which can be used to relieve pain in the muscles and joints associated with arthritis. It can also be used to relieve diabetic nerve pain, and may also be useful in helping to reduce symptoms of peripheral neuropathy associated with shingles.
It is a naturally-occurring compound which is found in chili peppers, which belong to the genus capsicum, from where the ointment gets its name. In large doses, it can be an irritant, as it produces a burning sensation with any tissues it comes into contact with. In its pure form, capsaicin is a colorless, hydrophobic, pungent compound which is crystalline to waxy in appearance and structure.
The compound may also have off-label uses, which should be determined by a qualified physician. Anecdotal reports suggest that it could be useful as a treatment for obesity, cancer and some cardiovascular conditions.
Like all medications, capsaicin may cause unwanted side effects along with its desired effects. The most common side effects reported by patients undergoing treatment with this medication include: burning, itching, pain, redness, dryness, swelling or soreness at the site of application.
As the patient continues to apply capsaicin topical ointment as prescribed by a doctor, some or all of these side effects should lessen. If side effects persist for a prolonged period or appear to get worse over time, the patient is advised to contact their doctor as soon as possible. In some instances, a doctor or healthcare professional may be able to advise the patient on a number of ways to alleviate these side effects while still experiencing the analgesic benefits of capsaicin.
The majority of patients will only experience minor side effects (if any at all) while undergoing treatment with capsaicin ointment, and in many cases the painkilling benefits of applying the cream will outweigh the negatives of the minor discomfort of any side effects.
Other side effects which are experienced rarely (albeit often enough to warrant mentioning) include: blurred vision, headache, dizziness, nervousness, changes in heart rate, pounding in the ears, bloating or swelling of the arms, face and extremities, an increased sensitivity to touch, an increased sensitivity to pain, weight gain, unsteadiness, tingling in the hands or feet, weakness in the hands or feet, muscle aches, fever, nausea, vomiting, changes in taste and/or abnormal skin color. Patients who experience any of these side effects to the point of discomfort should contact their doctor to discuss their current treatment.
Because this medication can cause unsteadiness and dizziness, patients are advised to refrain from driving or operating heavy machinery until it has been ascertained that it is safe to do so. Although this side effect is rare, patients should be cautious in order to avoid putting themselves or other road users at unnecessary risk.
As with all medicines, it is imperative that the patient only applies capsaicin ointment or patches only as prescribed by a qualified doctor. This means that patients should avoid applying more of the cream than advised, both in terms of dose size and frequency of application. In addition to this, patients should discontinue treatment with capsaicin when advised to do so by their doctor, even if they have a supply of the medication remaining.
In the treatment of postherpetic neuralgia, capsaicin should be applied to dry, non-irritated skin and allowed to soak in for 30 minutes on the feet, and 60 minutes when applied elsewhere. This treatment should only be applied every three months, under the supervision of a physician or suitable healthcare professional.
Capsaicin creams are commercially available in concentrations of 0.025, 0.075 and 0.1 per cent. The duration of treatment is dependent on the condition and the patient's response. Because treatment with the cream can cause a painful burning sensation, affected areas are often pre-treated with lidocaine cream prior to capsaicin application.
For general aches and pains such as strains, sprains, bruises, arthritis and muscular conditions, capsaicin should be applied three to four times per day. A thin film of the cream should be spread over the affected area(s) and gently rubbed in until completely absorbed. Unless the hands are being treated with the cream, they should be thoroughly washed with soap and warm water immediately after use. This treatment is generally not suitable for children under the age of 12, unless prescribed by a doctor. Safety and efficacy of this medication at standardized doses (3-4 times per day) have yet to be established in patients younger than 2 years of age.
The burning sensation associated with capsaicin comes as a result of its chemical reaction with sensory neurons. It binds to the TRP1 receptor, producing the same sensations as abrasive damage or excessive heat on the skin. The inflammation which occurs is as a result of the body's reaction to nerve stimulation.
Patients with sensitive skin may wish to wear nitrile gloves when handling and applying capsaicin cream in order to minimize the risk of irritation. Latex gloves should be avoided when handling this medicine as they do not provide sufficient protection.
Capsaicin cream may take weeks of application before the patient observes any benefit. In clinical studies, patients typically responded positively to treatment with this medication between 4 and 12 weeks of application. Patients are therefore advised to continue using the drug for a period advised by a doctor, even if they feel no initial benefit from the cream.
Patients are advised not to take double doses of the cream. If a patient misses a dose, they should simply take the next dose as planned and continue with treatment as normal. Increased dose application increases the risk of experiencing a burning sensation, redness and discomfort.
Although the risk of serious allergic reaction to this medicine is unlikely, patients should seek immediate medical attention if they experience a rash, swelling of the face/throat/tongue and have difficulty breathing.
Drugs can potentially interact with other chemicals or medications within the human body, and these interactions can change the effects of the medication. In some instances, interactions can cause one medication to become ineffective in treating a condition. In other instances, dangerous reactions or side effects can occur when two interacting medicines are combined. For these reasons, it is incredibly important for patients to keep a full, detailed list of all medications they are currently taking, including the frequency and dose size of each drug. This applies to herbal remedies, complimentary medicines, vitamins and supplements as well as prescribed medicines.
Below is a partial list of medications known to have interacted negatively with capsaicin. Patients who are currently undergoing treatment with any of these medicines should inform their doctor prior to applying capsaicin topical ointment:
Additionally, patients are advised to inform their doctor if they are taking any other substances which may increase tolerance to pain or induce drowsiness. This includes recreational substances such as alcohol, marijuana and cocaine, as well as any cough suppressants or painkillers that contain codeine or hydrocodone. Patients should check the ingredient listings of all medicines they are currently taking, as many drugs contain ingredients intended to cause drowsiness or relieve pain, even if the patient may not realise it.
In addition to discussing allergies and current drugs being taken, the patient should also be forthcoming about their medical history and current medical issues. This is so a doctor or healthcare professional can be certain that topical application of capsaicin can be completely safe.
Some patients may be allergic to hot peppers from the capsicum family, and this will create problems during treatment with capsaicin. Patients who are allergic to chilli peppers should avoid capsaicin topical cream, and should discuss an alternative treatment with their healthcare provider instead.
Patients who are allergic to lidocaine should avoid preventative treatment with lidocaine-based creams prior to/after capsaicin treatment. In some instances, a doctor may simply prescribe capsaicin cream without a lidocaine preventative measure. In other instances, they may prescribe an alternative treatment altogether.
Capsaicin use should be avoided prior to or shortly after taking a hot bath or shower, as this could potentially enhance the burning sensation caused by the medication. Patients should also avoid inhaling the vapors from the cream, as this can cause breathing difficulties and in some cases, make asthma worse than normal. It can also cause irritation to the eyes. If the cream inadvertently gets into the eyes, the patient should rinse the affected area with cold water. This medicine should not be used on broken or irritated skin either, as it may increase pain, discomfort and irritation.
Patients who currently suffer from high blood pressure (hypertension) or have recently been diagnosed with heart problems should avoid using capsaicin, as it may exacerbate existing congenital symptoms. Patients who are due to undergo an MRI scan should inform healthcare personnel prior to the procedure. This is because some topical creams may contain metals which could potentially cause burns during an MRI scan.
The safety of capsaicin use has not yet been determined in pregnant women. Those who are pregnant or intending to get pregnant are therefore advised to use capsaicin with caution, and should only use topical capsaicin cream if the benefits outweigh the risk. For further information on how capsaicin could potentially affect a developing fetus, patients are advised to consult their doctor or healthcare provider.
Capsaicin is excreted into human milk, although the effects in the nursing infant are not currently known. Nursing mothers should therefore exercise caution when taking this or any other medicine while breastfeeding.
Capsaicin should be stored in the container it was shipped in, at room temperature and out of the reach of children and pets. In addition to this, the manufacturer recommends that it should be stored away from excess heat, moisture or direct light. It is therefore unsuitable for storage on a shelf or in the bathroom, and should ideally be kept in a dedicated, locked medicine cabinet.
If the patient and doctor come to the conclusion that treatment with capsaicin is no loner necessary, or the medication reaches the end of its shelf life, it should be disposed of in a safe and hygenic manner. Capsaicin should not be disposed of down a drain or toilet unless a professional has specifically advised that this is an acceptable means of dispensation. Healthcare professionals, local waste disposal departments and pharmacists can all offer advice on how best to dispose of unwanted medications. Many pharmacies offer medication takeback schemes, where the patient can return unwanted or unused medications for proper disposal.
Capsaicin is a naturally-occurring substance which is effective in the treatment of certain aches and pains associated with arthritis and diabetes, as well as being a beneficial treatment for contact injuries such as sprains or strains encountered during sport.
Although it is a worthwhile treatment, great care should be taken by the patient to avoid exacerbating any existing conditions or causing inflammation and/or an uncomfortable burning sensation. Patient and doctor should work together in order to ascertain the optimal dose dependent on the physiology and condition of the patient, and to eliminate the possibility of any drug interactions prior to commencing treatment.
When used correctly, capsaicin can help alleviate symptoms of pain, giving the patient greater freedom of movement and independence.