How Topical Pain Relievers Work

Different topical products work through distinct mechanisms depending on their active ingredient:

• Counterirritants – ingredients like menthol, camphor, and methyl salicylate create a cooling or warming sensation that stimulates nerve endings in the skin, effectively distracting the nervous system from deeper pain signals (gate control theory)
• Anti-inflammatories (topical NSAIDs) – penetrate the skin to reach inflamed joints and soft tissue, blocking the same COX enzymes as oral NSAIDs but with far less systemic absorption
• Anesthetics – ingredients like lidocaine block nerve conduction in the treated area, temporarily numbing the skin and underlying tissue
• Capsaicin – derived from chili peppers, capsaicin depletes substance P — a neurotransmitter that carries pain signals — from local nerve endings. Initial application causes burning; with repeated use, pain signaling is reduced
• Salicylates – related to aspirin, absorbed through the skin to reduce local inflammation and pain
• Prescription compounded creams – custom-mixed formulations combining multiple agents (e.g., ketamine, gabapentin, cyclobenzaprine, amitriptyline) prepared by a compounding pharmacy based on a physician’s prescription

Over-the-Counter Options

Counterirritant creams and gels

• Menthol-based: Biofreeze, Icy Hot, Tiger Balm (white) — produce a cooling sensation; widely used for muscle soreness, back pain, and arthritis
• Methyl salicylate + menthol: Bengay, Icy Hot cream, Salonpas gel — warming and cooling combination; effective for joint and muscle pain
• Camphor-based: often combined with menthol; Vicks VapoRub is a well-known example used for muscle aches

Capsaicin creams

• Available in 0.025%–0.1% concentrations OTC (Zostrix, Capzasin)
• Must be applied consistently 3–4 times daily for several weeks to achieve full benefit
• Causes initial burning that decreases with continued use — this is normal and expected
• Wash hands thoroughly after application; avoid contact with eyes and mucous membranes
• Effective for osteoarthritis, post-herpetic neuralgia, and diabetic neuropathy

Topical salicylates

• Found in many OTC products; work similarly to aspirin at the local level
• Should be avoided by people with aspirin allergy and used cautiously in children (risk of Reye’s syndrome with salicylates)

OTC lidocaine creams and gels

• Provide temporary numbing for surface-level and minor musculoskeletal pain
• Useful for localized nerve pain, minor burns, and skin irritation

Prescription Topical Options

• Diclofenac sodium gel (Voltaren Arthritis Pain, 1%) – now available OTC; the 1.5% solution (Pennsaid) remains prescription; highly effective for osteoarthritis of the knee and hand with far less GI and cardiovascular risk than oral diclofenac. Apply to the affected joint area, not generalized muscle areas
• Lidocaine 5% cream or ointment – stronger anesthetic for neuropathic pain, post-herpetic neuralgia, and painful procedures
• Ketoprofen gel – a prescription topical NSAID used in some countries for joint and soft tissue pain
• Compounded topical formulations – customized by a compounding pharmacist; may include combinations of gabapentin, ketamine, amitriptyline, baclofen, and other agents for complex or refractory pain; evidence for efficacy varies and insurance coverage is inconsistent

Conditions That May Benefit

• Osteoarthritis (especially knee and hand) — strongest evidence for topical diclofenac
• Muscle strains, sprains, and overuse injuries
• Post-herpetic neuralgia (shingles pain)
• Diabetic peripheral neuropathy
• Myofascial pain and trigger points
• Minor back and neck muscle pain
• Tendinitis and bursitis

Advantages Over Oral Medications

• Targeted relief with significantly reduced systemic absorption
• Lower risk of GI, cardiovascular, and kidney side effects compared to oral NSAIDs
• No risk of liver damage (as with acetaminophen overdose)
• Suitable for older adults and others who cannot tolerate oral pain medications
• Can be used alongside oral medications for additive relief
• No first-pass metabolism through the liver

Tips for Safe and Effective Use

• Apply to intact, unbroken skin only — never on open wounds, rashes, or irritated skin
• Wash hands after application (unless treating the hands — then wash after the product has dried)
• Do not use heating pads or bandages over topical products unless directed, as this can increase absorption and risk of irritation
• Avoid contact with eyes, mouth, and mucous membranes
• For capsaicin products, expect an initial burning sensation — this is normal and diminishes with consistent use
• For topical NSAIDs, follow dosing instructions for the application area and daily maximum
• Inform your doctor of all topical products you use, especially before surgery or if combining with oral medications of the same class
• If a skin reaction (rash, blistering, severe irritation) develops, discontinue use and consult a healthcare provider