Ibuprofen provides pain relief for four to six hours per dose. Most adults can take 200 to 400 mg every four to six hours as needed, though the exact timing depends on the type of pain and whether you’re using over-the-counter or prescription strength.
How Long Pain Relief Lasts
Ibuprofen typically starts working within 30 to 60 minutes after you take it, and the pain-relieving effect lasts four to six hours. That window applies to standard over-the-counter tablets (200 mg) and the common two-tablet dose (400 mg). After that, the drug’s concentration in your blood drops enough that pain or inflammation can return.
Taking ibuprofen with food slows how quickly it’s absorbed, which can delay that initial relief. It won’t reduce the total amount your body absorbs, so the overall effect is the same. If you need faster relief, taking it on an empty stomach with a full glass of water gets it into your system sooner, though this can be harder on your stomach lining.
Hours Between Doses for Adults
For general pain like headaches, muscle aches, or dental pain, the standard interval is 400 mg every four to six hours. For menstrual cramps, the recommendation is the same 400 mg but on the tighter end of that range, every four hours, since cramping pain tends to be more persistent.
Prescription-strength ibuprofen (600 or 800 mg tablets) follows a slightly different schedule. At higher doses, it’s typically taken three to four times per day rather than on a strict hourly clock, with a maximum of 3,200 mg in 24 hours. Over-the-counter use should stay well below that ceiling. At 400 mg every four hours, you’d hit 2,400 mg across six doses in a day, which is generally considered the upper boundary for self-treatment.
Hours Between Doses for Children
Children need longer gaps between doses. The recommended interval is every six to eight hours, not the four to six hours used for adults. Dosing is based on your child’s weight rather than age whenever possible. If you don’t know your child’s current weight, age-based charts on the packaging serve as a backup.
Ibuprofen is not recommended for infants under six months old unless specifically directed by a pediatrician.
How Many Days You Can Take It
Beyond the hourly question, there’s a daily limit worth knowing. For pain, over-the-counter ibuprofen should not be used for more than 10 consecutive days. For fever, that limit drops to three consecutive days. Past those thresholds, the risks of stomach irritation, kidney strain, and cardiovascular effects start to climb.
The risks aren’t just theoretical. Regular daily use of ibuprofen can damage the stomach lining and interfere with kidney function, especially in people who are dehydrated or already have reduced kidney capacity. If your pain or fever hasn’t resolved within those timeframes, the underlying cause likely needs evaluation rather than more ibuprofen.
Timing It for Best Results
Since each dose covers roughly four to six hours, you can plan around your pain patterns. If you know your pain is worst in the morning, taking a dose 30 to 60 minutes before you need to be active gives the drug time to reach full effect. For post-workout soreness or menstrual cramps that hit on a predictable schedule, dosing proactively on that same 30-to-60-minute lead time helps you stay ahead of the pain rather than chasing it.
If you find that relief consistently fades closer to the four-hour mark, spacing doses at four hours is fine for short-term use. If the pain is manageable and you can stretch to six hours, that reduces your total daily intake and is easier on your stomach. The four-to-six-hour range is a window, not a fixed rule, so adjust based on how your body responds.