What topical treatments are recommended for a patient with a muscle strain?

Topical Treatment for Muscle Strain

For acute muscle strain, start with over-the-counter topical NSAIDs (diclofenac 1% gel or ibuprofen gel) applied 3-4 times daily to the affected area, as these provide the best evidence for pain relief with minimal systemic side effects.

First-Line Topical Therapy

Topical NSAIDs are the preferred initial treatment for acute muscle strains based on high-quality evidence demonstrating efficacy equivalent to oral NSAIDs without gastrointestinal or systemic adverse effects 1, 2.

Specific NSAID Formulations and Dosing:

• Diclofenac gel 1%: Apply to affected area 3-4 times daily; this formulation has the strongest evidence with an NNT of 1.8 for achieving at least 50% pain reduction 2
• Ibuprofen gel: Apply 3-4 times daily; NNT of 3.9 for marked improvement 2
• Ketoprofen gel: Apply 3-4 times daily; NNT of 2.5 for pain relief 2

Key advantage: Topical NSAIDs provide localized cyclo-oxygenase inhibition at the injury site while minimizing systemic exposure, resulting in significantly fewer gastrointestinal complications compared to oral NSAIDs (adjusted OR 1.45 vs 2.59 for GI bleeding) 1.

Alternative First-Line Options

Over-the-Counter Counterirritants:

• Menthol/camphor combinations with methyl salicylate (e.g., Bengay, Icy Hot): Apply 3-4 times daily for immediate symptomatic relief through counter-irritant effects 3, 4
• These work by activating and desensitizing epidermal nociceptors 5
• Important caveat: Menthol actually reduces blood flow to the treated area by 8-20% and causes vasoconstriction, which may theoretically impair healing despite providing symptomatic relief 6

Arnica:

• FDA-approved for topical relief of muscle aches and bruising 7
• Apply as directed on product labeling for symptomatic relief 7

Second-Line Topical Therapy (If First-Line Inadequate After 4 Weeks)

Capsaicin:

• Capsaicin cream 0.025-0.075%: Apply 3-4 times daily for 6 weeks 1, 3
• Mechanism: Desensitizes TRPV1 receptors, decreasing substance P release and pain transmission 1
• Critical counseling point: Warn patients about initial burning/stinging sensation that typically subsides with continued use 1
• NNT of 3 for clinical improvement in musculoskeletal conditions 1

Lidocaine:

• Lidocaine patches 5% (prescription) or 4% (OTC): Apply to affected area for up to 12-24 hours daily 3, 8
• Patches are superior to creams/gels because they deliver medication gradually over hours rather than requiring multiple applications 1, 8
• Particularly useful when pain persists beyond the acute phase 9

Compounded Options for Refractory Cases

If standard topical treatments fail after 4-6 weeks, consider prescription compounded formulations 3:

• Amitriptyline 1-2% + Ketamine 0.5-5%: Apply up to 3 times daily; works by blocking sodium channels and antagonizing NMDA receptors in peripheral nociceptive afferents 1, 3
• Gabapentin 6% ointment: Apply as directed for neuropathic pain component 3, 4
• Combination formulations: May include lidocaine, clonidine, and gabapentin for severe cases 1

Treatment Algorithm

1. Days 1-7: Rest, ice, compression, elevation (RICE protocol) + topical diclofenac or ibuprofen gel 3-4 times daily 10, 2
2. Weeks 2-4: Continue topical NSAID; add physical therapy to restore flexibility and strength as pain subsides 10
3. Week 4 assessment: If inadequate response, switch to capsaicin or lidocaine patches 3
4. Week 6-8: If still inadequate, consider compounded formulations or systemic therapy 3

Critical Pitfalls to Avoid

• Do not rely solely on menthol-based products for healing: While they provide symptomatic relief, they reduce blood flow to the area which may impair tissue recovery 6
• Do not apply topical NSAIDs to broken skin or open wounds 2
• Do not use capsaicin near eyes or mucous membranes; ensure patients wash hands thoroughly after application 1
• Trial each topical agent for minimum 4 weeks before declaring treatment failure, as some agents require time to achieve full effect 3, 8
• Application site reactions (erythema, dryness, burning) are common but usually mild and transient 2, 5

When to Escalate Care

Refer to specialist or consider systemic therapy if 3, 4:

• No improvement after 6-8 weeks of appropriate topical therapy
• Severe pain limiting function despite topical treatment
• Signs of complete muscle rupture or significant structural injury
• Development of chronic pain syndrome