How many hours does diclofenac (Nonsteroidal Anti-Inflammatory Drug (NSAID)) 50 mg provide relief from pain?

Duration of Pain Relief with Diclofenac 50 mg

Diclofenac 50 mg provides pain relief for approximately 6-7 hours in most patients with acute pain. 1

Efficacy of Diclofenac for Pain Relief

Short-term Pain Relief (Less than 2 hours)

• Moderate-certainty evidence shows that oral diclofenac reduces pain within 2 hours of administration compared to placebo (weighted mean difference on 10-cm VAS: -0.93 cm) 2
• When combined with acetaminophen, diclofenac provides slightly better pain relief within 2 hours (weighted mean difference: -1.11 cm) 2
• Diclofenac potassium (immediate-release) formulations provide faster onset of action compared to diclofenac sodium (enteric-coated) formulations 3

Duration of Pain Relief

• The weighted median duration of analgesia for diclofenac 50 mg is approximately 6.7 hours 1
• For diclofenac 100 mg, the duration extends slightly to about 7.2 hours 1
• Pain relief typically begins within 1-2 hours after oral administration, with peak plasma concentrations occurring 1.5 to 2.0 hours after ingestion in fasting subjects 4

Factors Affecting Duration of Pain Relief

Formulation Differences

• Diclofenac potassium (immediate-release) provides better pain relief than diclofenac sodium (enteric-coated) formulations 3
• Fast-acting formulations (dispersible products, solutions, and softgel formulations) have similar efficacy with an NNT of 2.4 for 50% pain relief 3
• Diclofenac sodium has more limited efficacy in acute pain settings 3

Dosage Considerations

• There is a graded improvement in efficacy as doses rise from 25 mg to 100 mg 3
• The number needed to treat (NNT) for at least 50% pain relief over 4-6 hours improves with increasing doses:
  • 25 mg: NNT of 2.8 1
  • 50 mg: NNT of 2.3 1
  • 100 mg: NNT of 1.9 1

Comparative Efficacy

• Diclofenac 50 mg is comparable in efficacy to ibuprofen 400 mg for pain relief 5
• In post-operative pain, diclofenac 50 mg has an NNT of 2.3 compared to placebo, while diclofenac 100 mg has an NNT of 1.8 5
• For acute migraine, diclofenac potassium 50 mg provides effective relief from pain and associated symptoms 6

Safety Considerations

• Single doses of diclofenac generally have low adverse event rates, similar to placebo 3
• For longer-term use, there are concerns about potential side effects including gastrointestinal issues, bleeding risk, and kidney injury 2
• When used for multiple doses, NSAIDs like diclofenac should be used with caution due to safety concerns 2

Clinical Application

• For acute musculoskeletal injuries, diclofenac is among the most effective interventions for pain reduction at both less than 2 hours and at 1-7 days 2
• Topical diclofenac is also effective and may be preferred in some situations due to lower systemic exposure 2
• For cancer pain management, diclofenac gel can be applied 3 times daily or as a patch (180 mg) once or twice daily 2

The evidence consistently shows that diclofenac 50 mg provides approximately 6-7 hours of pain relief for most patients, with onset beginning within 1-2 hours after administration. The potassium salt formulation (immediate-release) is preferred for acute pain due to faster onset of action.