For most adults, the standard dose is two over-the-counter ibuprofen tablets (400 mg total) every four to six hours as needed. Most store-bought ibuprofen comes in 200 mg tablets, so two pills is the recommended single dose for general pain, headaches, and menstrual cramps. You can take this dose up to three times a day, but you should not exceed 1,200 mg (six tablets) in 24 hours without medical guidance.
Standard Adult Dose
The effective dose for mild to moderate pain in adults and teenagers is 400 mg every four to six hours. Since over-the-counter tablets are typically 200 mg each, that means two tablets per dose. For menstrual cramps specifically, the same 400 mg dose applies, but it can be taken every four hours if pain is severe.
You don’t always need the full 400 mg. If your pain is mild, one tablet (200 mg) may be enough. But 400 mg is the dose most consistently shown to provide meaningful relief, and it’s what the Mayo Clinic lists as the standard adult dose for both general pain and cramps.
How Often You Can Take It
Wait at least four to six hours between doses. Taking it more frequently than every four hours increases your risk of stomach irritation and kidney strain without providing additional pain relief. Ibuprofen typically starts working within 20 to 30 minutes and peaks around one to two hours after you take it, so give the first dose time before reaching for more.
At 400 mg every six hours, you’d take three doses a day (1,200 mg total). At 400 mg every four hours, you could reach six tablets in a day. For self-treating without a prescription, staying at or below 1,200 mg per day is the safer target. Prescription doses for conditions like rheumatoid arthritis can go as high as 3,200 mg per day, but those doses are supervised by a doctor and divided into three or four portions throughout the day.
Dosing for Children
Children’s ibuprofen is dosed by weight, not by age. If you know your child’s weight, use that to calculate the dose rather than relying on age ranges on the box. The American Academy of Pediatrics recommends giving ibuprofen every six to eight hours as needed, which is less frequent than the adult schedule.
Ibuprofen should not be given to infants under six months old unless specifically directed by a pediatrician. It has not been established as safe in that age group, and the FDA has not approved its use for children younger than six months. Children’s formulations come as liquid suspensions and chewable tablets with lower concentrations, so always check the label for the correct strength before measuring a dose.
Take It With Food
Ibuprofen works by blocking the same chemical signals that protect your stomach lining, which is why it can cause nausea, stomach pain, and even ulcers with repeated use. Taking it at the end of a full meal or with an antacid significantly reduces this irritation. Swallowing ibuprofen on an empty stomach, especially first thing in the morning, is one of the most common reasons people experience side effects they could have avoided.
Who Should Take Less or Avoid It Entirely
If you have kidney disease, heart failure, or a history of stomach ulcers, ibuprofen can make those conditions worse even at standard doses. It reduces blood flow to the kidneys, so people with any degree of kidney impairment are at higher risk for further damage. Long-term use of six or more pills a day for three years or longer has been linked to a specific type of kidney damage called analgesic nephropathy.
People who take blood thinners, blood pressure medications, or other anti-inflammatory drugs need to be cautious about stacking ibuprofen on top of those treatments. The combination can amplify side effects or interfere with how well those medications work. If you’re already taking another pain reliever that contains ibuprofen or a related ingredient (like naproxen), adding standalone ibuprofen tablets means you’re doubling up without realizing it.
What Happens If You Take Too Much
Ibuprofen has a relatively wide safety margin compared to some other pain relievers. At doses below 100 mg per kilogram of body weight, most people experience no symptoms at all. For a 150-pound adult, that threshold is roughly 6,800 mg, well above what anyone should take intentionally.
Between 100 and 300 mg per kilogram, symptoms are usually limited to nausea, vomiting, stomach pain, and drowsiness. Above 300 mg per kilogram, the risk escalates to seizures, organ damage, and in rare cases, death. Children tend to tolerate accidental overdoses somewhat better than adults, with significant symptoms not usually appearing below 300 mg per kilogram, but any suspected overdose in a child warrants immediate medical attention.
The real danger with ibuprofen is not a single large dose but the cumulative effect of taking too much over days or weeks. Chronic overuse quietly damages the stomach, kidneys, and cardiovascular system in ways that don’t produce obvious warning signs until the damage is significant.