Ibu is short for ibuprofen, one of the most widely used over-the-counter pain relievers in the world. It belongs to a class of drugs called NSAIDs (nonsteroidal anti-inflammatory drugs) and works by reducing pain, inflammation, and fever. You’ll find it sold under brand names like Advil and Motrin, as well as generic store brands, typically in 200 mg tablets or capsules.
What Ibuprofen Treats
Ibuprofen is designed for temporary relief of minor aches and pains. The FDA-labeled uses include headaches, toothaches, backaches, menstrual cramps, muscle aches, minor arthritis pain, cold symptoms, and fever. It handles both the pain itself and the underlying inflammation that often causes it, which is what separates it from acetaminophen (Tylenol), a pain reliever that doesn’t target inflammation.
Prescription-strength ibuprofen is also used for more persistent conditions like rheumatoid arthritis, osteoarthritis, and moderate pain following surgery or injury. The core drug is identical; the difference is simply a higher dose under medical supervision.
How It Works in Your Body
When tissue is injured or irritated, your body produces chemicals called prostaglandins that trigger pain, swelling, and fever. Ibuprofen blocks the two enzymes (COX-1 and COX-2) responsible for making those prostaglandins. With less prostaglandin activity, you feel less pain, the swollen area calms down, and fever drops.
This dual enzyme blocking is also the source of ibuprofen’s side effects. COX-1, in particular, helps maintain the protective lining of your stomach, so suppressing it is what makes ibuprofen harder on your digestive system than some other pain relievers.
How Fast It Works and How Long It Lasts
Most people start feeling pain relief within 30 to 60 minutes of taking ibuprofen. Peak effect typically arrives around one to two hours, though some fast-absorbing formulations (like liquid-filled capsules) can reach peak levels in as little as 40 minutes. A single dose generally provides relief for six to eight hours, which is why the standard guidance is to take it no more than every six hours.
Dosing for Adults and Children
For adults and children 12 and older, the standard OTC dose is 200 to 400 mg every four to six hours as needed. The over-the-counter maximum is 1,200 mg in 24 hours. Prescription doses can go as high as 3,200 mg per day for conditions like arthritis, but that level requires medical monitoring.
Children under 12 are dosed by weight, not age. Infant and children’s formulations come in liquid concentrations designed for precise measuring. Ibuprofen is not recommended for babies under six months old. For children old enough to take it, the standard schedule is every six to eight hours, no more than four doses in 24 hours.
Stomach and Digestive Risks
The most common side effects of ibuprofen involve the stomach and intestines. Because the drug suppresses the enzyme that helps protect your gut lining, it can cause nausea, heartburn, and stomach pain even at normal doses. With longer or heavier use, the risk escalates to erosions, ulcers, and in serious cases, bleeding or perforation of the stomach or intestinal wall.
Taking ibuprofen with food or a full glass of water helps reduce stomach irritation. People who need it regularly for weeks or longer are at significantly higher risk for digestive complications, especially older adults, people with a history of ulcers, and those who drink alcohol frequently.
Heart and Stroke Risk
All NSAIDs, including ibuprofen, carry an FDA boxed warning (the most serious type) about cardiovascular risk. The risk of heart attack or stroke can appear as early as the first weeks of use and increases with higher doses and longer duration. Estimates of increased relative risk range from 10 to 50 percent or more, depending on dose.
This risk exists even in people without prior heart disease, though people who already have cardiovascular problems face a higher absolute risk. Studies of patients who used NSAIDs after a first heart attack found they were more likely to die in the following year compared to those who did not take NSAIDs. There is also an increased risk of heart failure with ongoing use.
For occasional use at OTC doses (a few days for a headache or muscle strain), the added cardiovascular risk is small for most healthy people. The concern grows with consistent, long-term use.
Pregnancy Warnings
The FDA recommends avoiding ibuprofen from 20 weeks of pregnancy onward. Before that cutoff, it was already standard advice to avoid NSAIDs after 30 weeks because of the risk of a heart-related complication in the unborn baby (premature closure of a blood vessel called the ductus arteriosus). In 2020, the FDA extended the warning earlier to 20 weeks after finding that NSAIDs can also reduce amniotic fluid by affecting fetal kidney function. Low amniotic fluid can lead to serious complications.
If ibuprofen is considered medically necessary between weeks 20 and 30, guidance calls for the lowest effective dose for the shortest possible time, ideally no longer than 48 hours.
Notable Drug Interactions
Ibuprofen interacts meaningfully with several common medications:
- Blood thinners: Ibuprofen increases the risk of bleeding when combined with anticoagulants like warfarin, because both drugs independently affect how your blood clots.
- Lithium: Ibuprofen can raise lithium levels in the blood by reducing how quickly the kidneys clear it. This interaction varies widely between individuals but can be enough to cause lithium toxicity.
- Blood pressure medications and diuretics: NSAIDs can blunt the effectiveness of these drugs by promoting fluid retention, working against the very thing the blood pressure medication is trying to do.
- Aspirin: If you take low-dose aspirin for heart protection, ibuprofen can interfere with aspirin’s ability to prevent blood clots. The typical recommendation is to take aspirin at least 30 minutes before ibuprofen or eight hours after.
Ibuprofen vs. Other OTC Pain Relievers
Ibuprofen is one of three main types of over-the-counter pain relievers. Acetaminophen (Tylenol) reduces pain and fever but does not address inflammation, making it less effective for swollen joints or muscle injuries. Naproxen (Aleve) is another NSAID that works the same way as ibuprofen but lasts longer (up to 12 hours per dose), so it requires fewer daily doses. The tradeoff is that naproxen takes longer to kick in.
Ibuprofen tends to be the go-to choice when you want relatively fast relief for something involving both pain and inflammation, like a sprained ankle, dental pain, or menstrual cramps. Acetaminophen is often preferred for people with stomach sensitivity or those on blood thinners, since it doesn’t carry the same GI or bleeding risks. For anyone choosing between them, the decision usually comes down to whether inflammation is part of the problem and how your stomach tolerates NSAIDs.