Can a patient with COVID-19 take Flexeril (cyclobenzaprine) for muscle aches?

Can a Patient with COVID-19 Take Flexeril for Muscle Aches?

Yes, a patient with COVID-19 can take Flexeril (cyclobenzaprine) for muscle aches, as there are no specific contraindications to its use in COVID-19 patients, and it is FDA-approved for acute painful musculoskeletal conditions. 1

Primary Recommendation

Cyclobenzaprine is indicated as an adjunct to rest and physical therapy for relief of muscle spasm associated with acute, painful musculoskeletal conditions 1. The drug should be used only for short periods (up to two or three weeks) because adequate evidence of effectiveness for more prolonged use is not available 1.

Preferred First-Line Alternatives

Before prescribing cyclobenzaprine, consider that acetaminophen (paracetamol) is the preferred first-line medication for post-COVID myalgia due to its superior safety profile 2. Acetaminophen can be dosed up to 2 grams per day, not exceeding 4 grams in 24 hours 2. This recommendation is particularly important because:

• Acetaminophen has no significant drug interactions with COVID-19 antivirals including lopinavir/ritonavir, remdesivir, hydroxychloroquine, tocilizumab, or interferon beta 3
• It is the safest option for patients with cardiovascular comorbidities 2
• Paracetamol is preferred to NSAIDs for COVID-19 patients until more evidence is available 4

When Cyclobenzaprine May Be Appropriate

If acetaminophen alone is insufficient for muscle aches, cyclobenzaprine can be added as it addresses muscle spasm specifically rather than just pain 1. The typical dosing is:

• Start with 5 mg three times daily, particularly in elderly patients or those with hepatic impairment 1
• May increase to 10 mg three times daily if needed and tolerated 1
• Limit use to 2-3 weeks maximum 1

Critical Drug Interaction Considerations

Be aware of potential interactions if the patient is on COVID-19 antivirals:

• Cyclobenzaprine is extensively metabolized by cytochromes P-450 3A4, 1A2, and to a lesser extent 2D6 1
• While specific interactions with COVID-19 antivirals are not documented in the evidence provided, the metabolic pathway suggests potential for interactions with drugs affecting these enzymes
• Monitor for increased sedation or side effects if combined with other medications 1

Special Populations Requiring Dose Adjustment

Elderly patients (≥65 years):

• Steady-state cyclobenzaprine levels are approximately 1.7-fold higher than in younger adults 1
• Elderly males show the highest increase (2.4-fold) 1
• Initiate with 5 mg dose and titrate slowly upward 1

Hepatic impairment:

• Both AUC and Cmax are approximately double in patients with hepatic impairment 1
• Use with caution in mild hepatic impairment, starting with 5 mg and titrating slowly 1
• Not recommended in moderate to severe hepatic impairment 1

Common Side Effects to Counsel Patients About

• Drowsiness is the most frequent adverse reaction 1
• Dry mouth occurs more frequently with cyclobenzaprine than with other muscle relaxants 1
• The effective half-life is 18 hours (range 8-37 hours), so sedation may persist 1

Important Clinical Context for COVID-19 Myalgia

Muscle aches in COVID-19 patients may have multiple underlying causes beyond simple muscle spasm:

• SARS-CoV-2 may directly cause damage to respiratory and skeletal muscles through viral infiltration via ACE-2 receptors 4
• Respiratory muscle dysfunction is prevalent in 88% of symptomatic Long-COVID patients 5
• Myalgias are common musculoskeletal manifestations of COVID-19 6

Comprehensive Management Approach

Do not rely solely on pharmacological management:

• Incorporate rest and physical therapy as cyclobenzaprine is indicated only as an adjunct 1
• Address biopsychosocial aspects including exercise, sleep hygiene, and healthy lifestyle 2
• Consider telemedicine for ongoing assessment and medication adjustments 2
• For severe or refractory symptoms, multidisciplinary pain management may be needed 2

Common Pitfalls to Avoid

• Do not use cyclobenzaprine for spasticity associated with neurological disease, as it has not been found effective for this indication 1
• Avoid prolonged use beyond 2-3 weeks without reassessment 1
• Do not combine with other CNS depressants without careful monitoring for additive sedation 1
• Be cautious with opioid prescriptions if muscle relaxants are insufficient, as psychological stress from COVID-19 may increase requirements and risk of misuse 2