Adults can take 200 to 400 mg of ibuprofen every four to six hours as needed, with a maximum of 1,200 mg in a 24-hour period when using over-the-counter strength. That four-to-six-hour window is the key number to remember, and spacing your doses correctly matters more than most people realize.
Standard Dosing for Adults
A single over-the-counter dose for adults and teenagers is 200 to 400 mg. Most OTC tablets come in 200 mg, so that’s one to two tablets at a time. You can repeat that dose every four to six hours while symptoms persist, but you should not exceed 1,200 mg (six 200 mg tablets) in 24 hours without a doctor’s guidance.
For menstrual cramps specifically, the effective dose is 400 mg every four hours as needed. The shorter interval reflects the nature of that type of pain, but the daily ceiling still applies.
Prescription-strength ibuprofen can go higher, sometimes up to 800 mg per dose and 3,200 mg per day for conditions like rheumatoid arthritis. Those doses carry significantly more risk and are only appropriate under medical supervision.
Why the Four-to-Six-Hour Gap Matters
Ibuprofen has a half-life of about 2.5 hours, meaning your body clears half the drug from your bloodstream in that time. Its pain-relieving effect typically lasts four to six hours, which is why the dosing interval matches that window. Taking it sooner than every four hours stacks doses in your system and raises your risk of side effects, particularly stomach irritation, without providing meaningfully better relief.
If your pain returns well before the four-hour mark, that’s a signal that ibuprofen alone may not be the right approach for what you’re dealing with, not that you need a higher frequency.
Dosing for Children
Children’s doses are calculated by weight, not age. The standard range is 4 to 10 mg per kilogram of body weight per dose, given every six to eight hours. Notice that’s a longer gap than for adults. The maximum single dose for a child is 400 mg, and the total daily amount should not exceed 40 mg per kilogram or 1,200 mg, whichever is lower.
Children’s ibuprofen products come in liquid concentrations with dosing syringes, and the packaging includes weight-based charts. Using those charts rather than guessing by age gives a more accurate and safer dose.
How Many Days in a Row Is Safe
The frequency question isn’t just about hours between doses. It’s also about how many consecutive days you take it. The general guideline is no more than 10 days in a row for pain, and no more than 3 days in a row for fever. If you still need ibuprofen after those windows, something worth investigating is likely going on.
The most common side effect at routine doses is damage to the lining of the stomach and upper digestive tract. This type of injury tends to build gradually with repeated use. The gastrointestinal lining can usually recover from occasional short-term use, but chronic daily dosing, even at low amounts, can cause microbleeding and erosion over time. The greatest damage to the stomach lining from anti-inflammatory drugs tends to occur within 24 hours of a dose, and repeated daily dosing doesn’t give the tissue time to heal between rounds.
If You Also Take Low-Dose Aspirin
People who take daily low-dose aspirin for heart protection need to be careful with ibuprofen timing. Ibuprofen can block aspirin’s ability to prevent blood clots if the two are taken too close together. The FDA recommends taking ibuprofen at least 30 minutes after your aspirin, or at least 8 hours before your next aspirin dose. Either window preserves aspirin’s protective effect. This applies to immediate-release (non-enteric-coated) aspirin specifically.
Making Each Dose More Effective
Taking ibuprofen with food or a full glass of water reduces stomach irritation and can help it absorb more consistently. If you’re using it for something predictable, like post-exercise soreness or menstrual cramps that follow a pattern, taking it at the first sign of discomfort works better than waiting until pain peaks. Ibuprofen blocks the production of inflammatory chemicals, so catching the process early means less inflammation to fight in the first place.
If you find yourself reaching for ibuprofen at the maximum frequency (every four hours, three times a day) for several days running, you’re at the upper edge of safe self-treatment. Alternating ibuprofen with acetaminophen is one strategy that lets you manage pain on a tighter schedule without exceeding the limits of either drug, since they work through completely different mechanisms and don’t share the same side-effect profile.