What are the first‑line non‑opioid analgesics for an acute headache in an adult with no known contraindications?

First-Line Non-Opioid Analgesics for Acute Headache

For acute headache in adults, NSAIDs—specifically ibuprofen 400–800 mg, naproxen sodium 500–825 mg, or aspirin 1000 mg—are the recommended first-line therapy for mild-to-moderate pain, while acetaminophen 1000 mg is an alternative when NSAIDs are contraindicated. 1

Evidence-Based First-Line Options

NSAIDs (Preferred)

• Ibuprofen 400–800 mg is a first-line agent with Level A evidence for efficacy in acute headache treatment. 1, 2
• Naproxen sodium 500–825 mg demonstrates strong efficacy and can be repeated every 2–6 hours as needed, with a maximum daily dose of 1.5 g. 1, 3
• Aspirin 1000 mg (or 650–1000 mg every 4–6 hours, maximum 4 g daily) has robust evidence supporting its use as first-line therapy. 1, 4
• Diclofenac potassium is another NSAID with Level A evidence for acute migraine treatment. 2, 3

Acetaminophen (Alternative)

• Acetaminophen 1000 mg is effective for mild-to-moderate headache, though less effective than NSAIDs. 1, 5
• Acetaminophen alone at lower doses (500–650 mg) has not demonstrated statistically significant benefit; the full 1000 mg dose is required. 1
• This is the safest option during pregnancy and for patients with NSAID contraindications. 1, 6

Combination Therapy (Enhanced Efficacy)

• Acetaminophen 1000 mg + aspirin 500–1000 mg + caffeine 130 mg provides superior efficacy compared to single agents, achieving pain reduction in 59.3% of patients at 2 hours. 1, 5
• Note that acetaminophen alone is ineffective; the combination with aspirin and caffeine is what provides benefit. 4

Route Selection Based on Severity

Oral Route (Standard)

• Oral NSAIDs or acetaminophen should be taken at the earliest sign of headache for maximum effectiveness. 1, 3

Parenteral Route (Severe Headache)

• Ketorolac 30 mg IV (or 60 mg IM for patients under 65 years) provides rapid onset with approximately 6 hours of duration and minimal rebound headache risk. 1, 7
• Ketorolac is ideal for severe headache requiring injectable therapy when oral agents are insufficient. 1

Adjunctive Antiemetic Therapy

• Metoclopramide 10 mg IV or oral provides synergistic analgesia beyond its antiemetic effect through central dopamine receptor antagonism. 1, 4
• Prochlorperazine 10 mg IV is equally effective and may have fewer side effects than metoclopramide. 1
• Administer antiemetics 20–30 minutes before NSAIDs to enhance absorption and improve outcomes. 4

Critical Frequency Limitation

All acute headache medications must be limited to ≤2 days per week (≤10 days per month) to prevent medication-overuse headache, which paradoxically increases headache frequency and can lead to daily headaches. 1, 2

Contraindications and Precautions

NSAIDs

• Contraindicated in active GI bleeding, severe renal impairment (creatinine clearance <30 mL/min), aspirin/NSAID-induced asthma, and uncontrolled hypertension. 1
• Use ketorolac with caution in patients with renal impairment, history of GI bleeding, or heart disease. 1

Acetaminophen

• Monitor total daily intake to ensure it does not exceed 4000 mg per day from all sources. 1
• Acetaminophen is the safest option when hypertension is uncontrolled, as NSAIDs can further elevate blood pressure. 1

Medications to Absolutely Avoid

• Opioids (hydrocodone, oxycodone, morphine, codeine, tramadol) should never be used as first-line therapy because they provide limited efficacy, carry high risk of dependence, and cause rebound headaches. 1, 7
• Butalbital-containing compounds should be avoided due to high risk of medication-overuse headache and dependency. 1, 7

When to Escalate Therapy

• If inadequate response after 2–3 headache episodes with NSAIDs or acetaminophen, consider escalation to triptans for moderate-to-severe attacks. 1, 3
• If acute medications are needed more than twice weekly, initiate preventive therapy immediately rather than increasing frequency of acute treatment. 1, 2