Ibuprofen at its highest over-the-counter dose (400 mg) is the strongest single-ingredient OTC pain reliever for most types of acute pain. But the most effective OTC option overall is combining ibuprofen with acetaminophen, which outperforms even prescription opioids in clinical trials. The answer depends partly on the type of pain you’re dealing with and how your body handles these drugs.
How OTC Pain Relievers Rank
Pain researchers use a metric called “number needed to treat” (NNT) to compare how well analgesics work. It measures how many people need to take a drug for one person to get at least 50% pain relief over four to six hours. A lower number means a more effective drug. Here’s how the main OTC options stack up:
- Ibuprofen 400 mg: NNT of 2.4, meaning roughly 1 in 2.4 people get meaningful relief
- Naproxen 440 mg: NNT of 2.3
- Aspirin 1200 mg: NNT of 2.4
- Ibuprofen 200 mg: NNT of 2.7
- Naproxen 220 mg: NNT of 3.1
- Acetaminophen 1000 mg: NNT of 3.8
- Aspirin 600 mg: NNT of 4.4
At standard OTC doses, ibuprofen and naproxen are close in strength. Both belong to the NSAID class (non-steroidal anti-inflammatory drugs), which as a group consistently outperforms acetaminophen. Acetaminophen at its maximum single dose of 1,000 mg is measurably weaker than a standard 400 mg ibuprofen tablet. For context, common NSAIDs at typical doses actually score better in these trials than 10 mg of injected morphine, which has an NNT of 2.9.
Why Combining Ibuprofen and Acetaminophen Wins
The single most effective OTC pain strategy isn’t one drug. It’s taking ibuprofen and acetaminophen together. A Cochrane review found that 400 mg ibuprofen plus 1,000 mg acetaminophen gave 73% of people at least 50% pain relief, compared to 52% with ibuprofen alone and just 7% with placebo. That combination has an NNT of 1.5, better than nearly every analgesic studied, including prescription options.
This works because the two drugs block pain through completely different pathways. NSAIDs like ibuprofen reduce inflammation at the injury site by blocking enzymes that produce pain-signaling chemicals called prostaglandins. Acetaminophen works in the brain and spinal cord, dampening pain signal transmission in the central nervous system. Taking both means you’re interrupting pain at both ends of the chain. The American Dental Association endorses this combination as more effective than any opioid-containing regimen, based on data from over 58,000 patients after wisdom tooth extractions.
A combination tablet containing both drugs is now available OTC. The standard dose is two tablets every eight hours, with a maximum of six tablets per day.
Speed and Duration of Relief
How fast you feel relief matters when you’re in pain. Ibuprofen and acetaminophen both start working within 30 to 60 minutes when taken orally, but they differ in how long they last. Ibuprofen provides six to eight hours of relief per dose, while acetaminophen lasts four to six hours.
Naproxen is the slowest to kick in among the common OTC options, but it has the longest duration. A single dose can control pain for up to 12 hours, which is why it’s dosed twice daily rather than every four to six hours. If your pain is steady throughout the day and you don’t want to keep re-dosing, naproxen has a practical advantage.
Formulation matters too. Liquid-filled ibuprofen capsules (sometimes labeled “liquigels”) reach peak pain relief faster than standard tablets and last longer than acetaminophen, even though the active ingredient and dose are identical to a regular tablet.
Matching the Pain Reliever to the Pain
For pain caused by inflammation (dental pain, sprains, menstrual cramps, arthritis flares), NSAIDs are the clear winner because they directly target the inflammatory process driving the pain. Acetaminophen doesn’t reduce inflammation at all, so it’s working with one hand tied behind its back for these conditions.
For headaches and fevers without significant inflammation, acetaminophen works reasonably well and carries fewer risks for most people. It’s also the safer option during pregnancy and for people who can’t tolerate NSAIDs.
For moderate to severe acute pain, like after a dental procedure or an injury, clinical guidelines recommend the ibuprofen-acetaminophen combination as first-line treatment. The recommended approach for moderate to severe pain is 400 to 600 mg of ibuprofen plus 500 mg of acetaminophen every six hours for the first 24 hours, then as needed after that.
Ibuprofen vs. Naproxen
These two NSAIDs are often treated as interchangeable, but they have meaningful differences. At equivalent OTC doses, their pain-relieving power is similar. Naproxen’s advantage is convenience: you take it every 12 hours instead of every 4 to 6. Ibuprofen’s advantage is flexibility, since the shorter duration means it clears your system faster if you experience side effects.
Neither is categorically “stronger.” If one hasn’t worked well for you, it’s worth trying the other, because individual responses to specific NSAIDs vary quite a bit.
Safety Trade-offs With Stronger Options
The strongest OTC choices are also the ones that carry the most risk when used incorrectly. NSAIDs can cause stomach ulcers and gastrointestinal bleeding, especially at higher doses, with prolonged use, or in people over 65. The risk climbs significantly if you’re also taking aspirin, blood thinners, corticosteroids, or certain antidepressants (SSRIs). A history of stomach ulcers is a major red flag for NSAID use.
NSAIDs also raise cardiovascular risk. For people with existing heart disease or elevated cardiovascular risk factors, these drugs are more likely to cause problems. This applies to all NSAIDs, including ibuprofen and naproxen, though the degree of risk varies between them.
Acetaminophen is gentler on the stomach and cardiovascular system, but it’s hard on the liver. The maximum safe amount is 4,000 mg (4 grams) in 24 hours, and that ceiling drops if you drink alcohol regularly. Because acetaminophen is an ingredient in dozens of products (cold medicines, sleep aids, combination pain relievers), it’s easy to accidentally exceed the limit without realizing it.
Aspirin, while an effective pain reliever at higher doses, causes more gastrointestinal side effects than ibuprofen or naproxen at equivalent pain-relieving doses, and its NNT is worse. It’s rarely the best OTC choice purely for pain relief, though it remains important for cardiovascular protection at low doses.
The Bottom Line on Strength
If you’re choosing a single OTC pill, ibuprofen 400 mg gives you the best balance of proven efficacy, fast onset, and reasonable duration. If you need something stronger, combining ibuprofen 400 mg with acetaminophen 500 to 1,000 mg is the most powerful OTC pain relief available, rivaling or exceeding prescription painkillers for many types of acute pain. Acetaminophen alone is the weakest of the major OTC options for pain but remains the right choice when NSAIDs aren’t safe for you.