What is the safest and most appropriate muscle relaxant for a 70‑year‑old man with isolated shoulder pain?

Best Muscle Relaxant for Elderly Patients

For a 70-year-old man with isolated shoulder pain, avoid all muscle relaxants if possible and use topical analgesics or scheduled acetaminophen instead; if a muscle relaxant is absolutely necessary, tizanidine 2 mg up to three times daily is the safest choice, but only for ≤2 weeks. 1

Why Muscle Relaxants Should Be Avoided in the Elderly

• Muscle relaxants as a class are listed in the American Geriatrics Society Beers Criteria as potentially inappropriate medications for older adults due to anticholinergic effects, sedation, and increased risk of falls. 1

• Most muscle relaxants do not actually relax skeletal muscle directly and have no evidence of efficacy in chronic pain—their mechanism likely relates to sedative properties rather than true muscle relaxation. 1, 2

• All skeletal muscle relaxants increase total adverse events by 50% and double the CNS adverse events compared to placebo, with common effects including somnolence, dizziness, dry mouth, and increased fall risk. 2

• Older adults using skeletal muscle relaxants have a significantly increased risk of injury (OR 1.32,95% CI 1.16-1.50). 3

Preferred Non-Pharmacologic and Alternative Approaches

• The American College of Physicians recommends considering non-pharmacological approaches for muscle spasm management first. 1

• Topical analgesics (lidocaine or diclofenac gels) can relieve focal musculoskeletal pain in older adults with fewer systemic side effects compared with oral agents (moderate evidence, 2020 systematic review). 1

• Scheduled acetaminophen may be effective for mild to moderate musculoskeletal pain in elderly patients. 1

If a Muscle Relaxant Is Absolutely Required: Tizanidine vs. Baclofen

Tizanidine: The Preferred Option

• The American Geriatrics Society recommends tizanidine as a preferred muscle relaxant option for elderly patients, starting at 2 mg up to three times daily. 1

• Tizanidine demonstrated efficacy in 8 randomized clinical trials for acute low back pain, providing moderate short-term pain relief (2-4 days) that was statistically superior to placebo. 1

• Guidelines advise using tizanidine for ≤2 weeks maximum when treating acute muscle spasm in elderly patients to minimize cumulative adverse effects. 1

• Monitor for hypotension and sedation, the most common dose-related adverse effects. 4

• Tizanidine requires monitoring for hepatotoxicity, which is generally reversible. 4

Baclofen: Higher Risk in the Elderly

• While the American Geriatrics Society lists baclofen as an option (starting dose 5 mg three times daily, maximum 30-40 mg/day), recent 2023 comparative safety data shows baclofen carries significantly higher risks than tizanidine. 1, 5

• Older adults newly started on baclofen had a 54% greater risk of injury (HR 1.54,95% CI 1.21-1.96) and a 233% greater risk of delirium (HR 3.33,95% CI 2.11-5.26) compared to tizanidine. 5

• A 2024 study confirmed baclofen was associated with a 68% higher risk of fall compared to tizanidine (SHR 1.68,95% CI 1.20-2.36). 6

• Baclofen is approved primarily for spasticity caused by upper-motor-neuron disorders (multiple sclerosis, spinal cord injury, cerebral palsy) and lacks evidence for efficacy in peripheral musculoskeletal pain. 4

• Prescribing baclofen for peripheral shoulder pain can worsen functional impairment because it commonly produces muscle weakness, which may further limit activities. 4

• Baclofen must never be discontinued abruptly—requires slow tapering to avoid withdrawal symptoms including delirium, seizures, and CNS irritability. 1

Muscle Relaxants to Absolutely Avoid in the Elderly

Cyclobenzaprine

• The American Geriatrics Society recommends avoiding cyclobenzaprine in elderly patients as it is structurally similar to tricyclic antidepressants with comparable adverse effect profiles. 1

• Cyclobenzaprine is listed in polypharmacy management guidelines as a medication with risks in older adults due to CNS impairment, delirium, slowed comprehension, and falling. 1

• Cyclobenzaprine is essentially identical to amitriptyline with similar anticholinergic side effects and potential toxicity in overdose. 2

• Cyclobenzaprine was associated with increased risk of injury in older adults (OR 1.22,95% CI 1.02-1.45). 3

Carisoprodol

• Carisoprodol should be avoided in elderly patients due to its high risk of sedation and falls, and has been removed from the European market due to concerns about drug abuse. 1

• Carisoprodol is classified as a controlled substance with substantial abuse and addiction potential. 1

• Carisoprodol was associated with the highest risk of injury among muscle relaxants (OR 1.73,95% CI 1.04-2.88). 3

Methocarbamol

• Methocarbamol elimination is significantly impaired in patients with liver and kidney disease. 1

• Methocarbamol can cause drowsiness, dizziness, and cardiovascular effects including bradycardia and hypotension. 1

• Methocarbamol was associated with increased risk of injury (OR 1.42,95% CI 1.16-1.75). 3

Metaxalone

• Metaxalone is contraindicated in patients with significant hepatic or renal dysfunction. 1

• Metaxalone has multiple central nervous system adverse effects, including drowsiness, dizziness, and irritability. 1

Orphenadrine

• Orphenadrine is listed in the Beers Criteria as potentially inappropriate for older adults due to its strong anticholinergic properties. 1

• Orphenadrine has anticholinergic properties that can cause confusion, anxiety, tremors, urinary retention, and cardiovascular instability. 1

• Orphenadrine should be used with caution in patients with cardiac issues and in the elderly. 1

Critical Dosing and Duration Principles

• Start with the lowest possible effective dose and use muscle relaxants for the shortest duration necessary (American Geriatrics Society). 1

• Maximum treatment duration should be 7-14 days for acute pain; patients requiring treatment beyond this should be re-evaluated to confirm diagnosis and consider alternative therapies. 4, 2

• Avoid prescribing muscle relaxants with other medications that have anticholinergic properties. 1

• Muscle relaxants should be avoided in frail patients with mobility deficits, weight loss, weakness, or cognitive deficits. 1

Special Consideration for Shoulder Pain

For isolated shoulder pain in a 70-year-old without evidence of CNS pathology (spinal cord injury, multiple sclerosis, cerebral palsy), there is no true spasticity present—only peripheral musculoskeletal tightness. 4 In this context:

• Muscle relaxants are not appropriate because they do not address peripheral muscle tightness and may cause more harm than benefit. 1, 4

• Focus on topical NSAIDs, physical therapy, and if needed, short-term oral NSAIDs combined with acetaminophen. 1

• If neuropathic pain is suspected, consider gabapentinoids (pregabalin, gabapentin) or duloxetine instead, which have stronger evidence for neuropathic pain in elderly patients. 1