What Causes the Sensation?
Many over-the-counter topical pain relief creams rely on ingredients known as 'counterirritants' to create a distracting sensation on the skin. These ingredients work by stimulating nerve endings on the skin's surface, overwhelming the nerves' ability to send pain signals to the brain. Instead of feeling the underlying ache or pain, the user feels a different sensation, such as coolness or warmth. However, understanding the difference between this intended sensation and a dangerous, adverse reaction is key to safe use.
The Role of Counterirritants
- Menthol and Methyl Salicylate: These are common active ingredients that produce a cooling, then warming sensation. Menthol, derived from peppermint, and methyl salicylate, from wintergreen, stimulate thermoreceptors in the skin. A mild, tingling warmth or coolness is expected. However, high concentrations, especially when combined, have been linked to a higher risk of serious burns.
- Capsaicin: This is the natural component that makes chili peppers hot. Capsaicin works by depleting a neurotransmitter called Substance P, which is responsible for sending pain signals. Initially, capsaicin creams cause a warm tingling or burning sensation, but this typically diminishes with repeated use over time as the nerves become desensitized. A severe or persistent burning sensation is not the intended effect.
- Lidocaine: As a topical anesthetic, lidocaine works by numbing the skin to block nerve signals completely. A mild tingling or change in sensation is normal, but it should not cause a painful, burning feeling.
Distinguishing Normal Sensation from a Problem
It's important to be able to tell the difference between the intended, therapeutic sensation and a genuine skin injury. Here is a breakdown of what to expect and what to be concerned about.
Signs of a Normal Reaction
- Mild Tingling or Warmth: A slight tingling, cooling, or warm sensation that is not intensely painful. This should feel like a distracting warmth or coolness, not a hot, sharp sting.
- Quickly Fading Sensation: The sensation should subside within a few minutes after application as your skin becomes accustomed to the product. With capsaicin, the initial burn-like feeling should decrease with regular use.
- No Visible Skin Damage: The skin remains its normal color or may show slight, temporary pinkness. There should be no blistering, swelling, or peeling.
Warning Signs of a Serious Burn
- Intense, Painful Burning: A deep, stinging, or painful burning sensation that is clearly more than just a mild distraction.
- Blistering or Swelling: The appearance of blisters, severe redness, or swelling on the skin where the cream was applied. This is a sign of a potential chemical burn.
- Increasing Pain: If the pain and burning escalate over time or after repeated applications, it indicates that the skin is being damaged.
- Allergic Reaction: In rare cases, a burning sensation can be part of a severe allergic reaction, which may also include a rash, hives, swelling of the face/throat, or difficulty breathing. This requires immediate medical attention.
Comparison of Common Topical Pain Relief Ingredients
Feature | Menthol / Methyl Salicylate | Capsaicin | Lidocaine | Diclofenac (Prescription NSAID) |
---|---|---|---|---|
Mechanism | Stimulates thermoreceptors to distract from pain. | Desensitizes nerve endings by depleting Substance P. | Numbes skin to block pain signals. | Inhibits prostaglandins to reduce inflammation and pain. |
Expected Sensation | Mild cooling or warming tingle. | Initial warm tingling or mild burning that fades over time. | Mild tingling or change in skin sensation. | Typically no distracting sensation. |
Serious Side Effect | Severe burns possible, especially with high concentrations or added heat. | Severe burning and blistering, especially with high concentrations. | Increased or unusual pain, potentially from masking injury. | Skin reactions like redness, scaling, or peeling at application site. |
Key Precaution | Avoid using with heat sources or tight bandages. | Use gloves when applying, avoid eyes and mucous membranes. | Do not apply to damaged skin. | Avoid sunlight exposure after application. |
Factors that Increase the Risk of Burns
Several actions can exacerbate the risk of a severe reaction from topical pain relievers. Avoiding these practices is crucial for your safety:
- Applying Heat: The FDA explicitly warns against using heating pads, heat lamps, or hot water bottles on an area treated with topical pain relievers. The combination can intensify the effects of the active ingredients and lead to severe chemical burns.
- Using on Damaged Skin: Applying the cream to broken, scraped, or irritated skin can cause the ingredients to absorb too quickly and deeply, increasing the risk of a strong, painful reaction.
- Tight Bandaging: Covering the application site with a tight bandage can trap the cream and increase absorption, potentially leading to a burn.
- High Concentration: Creams with higher concentrations of active ingredients, particularly menthol and methyl salicylate, carry a greater risk of adverse reactions.
- Individual Sensitivity: Reactions to these ingredients can vary widely between people. Some individuals with sensitive skin are more susceptible to irritation and burns. It's always best to perform a patch test on a small area of skin before widespread application.
What to Do If You Experience a Serious Burn
If you experience severe pain, swelling, or blistering after applying a pain relief cream, take the following steps immediately:
- Stop Use Immediately: Wash the affected area thoroughly with cool water and soap to remove all traces of the cream.
- Do Not Apply More Cream or Heat: Avoid further application of the product or any additional heat to the area.
- Seek Medical Attention: If symptoms persist or worsen, or if blisters appear, seek medical help immediately. Some burns have required hospitalization, and a medical professional can provide the best care for the injury.
Conclusion
In summary, while a mild cooling or warming sensation from a pain relief cream can be a normal part of its pharmacological action, a painful, intense burning sensation is not. It's a critical distinction that can prevent serious skin injury. Always follow the manufacturer's instructions carefully, avoid common risk factors like applying heat or tight bandages, and listen to your body. If the sensation is more than a mild tingle or warmth and becomes painful, blistering, or swelling occurs, discontinue use and seek immediate medical help. For further guidance on medication use and safety, consult resources like the FDA or a trusted healthcare provider, especially before using new or different topical treatments.