Ibuprofen is a nonsteroidal anti-inflammatory drug, commonly called an NSAID. It belongs to the same drug class as aspirin and naproxen. You probably know it by brand names like Advil and Motrin in the U.S., or Nurofen in the U.K. and Australia. It’s one of the most widely used medications in the world, available both over the counter and by prescription, and it works by reducing pain, inflammation, and fever.
How Ibuprofen Works in Your Body
Your body produces chemicals called prostaglandins at the site of an injury or infection. Prostaglandins trigger inflammation, swelling, and pain, and they also raise your body temperature when you’re sick. Ibuprofen blocks the enzymes responsible for making these chemicals. Specifically, it prevents a substance called arachidonic acid from reaching the enzymes that would convert it into prostaglandins. With fewer prostaglandins circulating, you feel less pain, swelling goes down, and fever drops.
Unlike aspirin, which permanently disables these enzymes, ibuprofen blocks them temporarily. That’s why its effects wear off after several hours and you need to take another dose.
What Ibuprofen Treats
Over-the-counter ibuprofen is used for everyday complaints: headaches, muscle aches, backaches, toothaches, menstrual cramps, the common cold, and fever. It’s a go-to for mild to moderate pain that doesn’t require something stronger.
At prescription strength, ibuprofen is also used for chronic inflammatory conditions. These include osteoarthritis, rheumatoid arthritis, ankylosing spondylitis (a type of arthritis that mainly affects the spine), psoriatic arthritis, and gout flares. In these cases, it’s treating ongoing inflammation rather than just dulling pain temporarily.
OTC vs. Prescription Strength
Over-the-counter ibuprofen comes in 200 mg tablets. The standard adult dose is one to two tablets (200 to 400 mg) every four to six hours. Some physicians recommend taking three tablets (600 mg) at a time for stronger relief, which is essentially a prescription-level dose using OTC pills. Prescription ibuprofen is available in higher strengths, typically 400 mg, 600 mg, or 800 mg tablets, for people managing chronic conditions who need consistent, higher doses under medical supervision.
How Quickly It Works
How fast ibuprofen kicks in depends on the formulation. Standard tablets like Motrin IB take about two hours to reach peak levels in your blood when taken on an empty stomach. Liquid-filled capsules like Advil Liqui-Gels are faster, peaking around 40 to 50 minutes. Sodium ibuprofen formulations are faster still, reaching peak concentration in roughly 30 to 35 minutes. Eating before you take ibuprofen slows absorption noticeably, pushing peak time closer to 90 minutes regardless of formulation.
The typical dosing schedule is every four to six hours, which reflects how long the effects last before prostaglandin production ramps back up.
Dosing for Children
Children’s ibuprofen doses are based on weight, not age. It should not be given to babies under six months old. Children’s formulations come as liquid drops (50 mg per 1.25 mL) and oral suspension (100 mg per 5 mL), plus chewable 100 mg tablets for older kids. A child weighing 24 to 35 pounds, for example, gets 5 mL of the liquid or one chewable tablet. A child weighing 72 to 95 pounds gets 15 mL of liquid or 1.5 adult-strength tablets. Always go by the weight listed on the packaging rather than guessing based on age.
Side Effects and Risks
For occasional use at normal doses, ibuprofen is well tolerated by most people. The most common side effects are stomach-related: nausea, heartburn, and upset stomach. Taking it with food helps. These GI effects happen because the same prostaglandins that cause pain also protect the stomach lining. When ibuprofen suppresses them, your stomach becomes more vulnerable to acid.
With long-term or high-dose use, the risks increase. Prolonged use can lead to stomach ulcers or bleeding, kidney strain, and elevated cardiovascular risk. These concerns apply to all NSAIDs, not just ibuprofen, and they’re the main reason this class of drugs isn’t meant for daily use over months without medical oversight.
Who Should Avoid Ibuprofen
The FDA warns against using ibuprofen or any NSAID after 20 weeks of pregnancy. At that stage, NSAIDs can cause kidney problems in the developing baby, leading to dangerously low amniotic fluid. After 30 weeks, the risk extends to heart complications for the baby. The one exception is low-dose aspirin (81 mg), which is sometimes prescribed during pregnancy for specific conditions.
People with a history of stomach ulcers, kidney disease, or heart disease should be cautious with ibuprofen. Those with aspirin-sensitive asthma may also react to ibuprofen, since both drugs affect the same enzyme pathway.
Interactions With Other Medications
The most notable interaction is between ibuprofen and low-dose aspirin. Many people take a daily 81 mg aspirin to protect against heart attack or stroke. Ibuprofen competes for the same binding site on the enzyme that aspirin targets. The difference is that aspirin permanently disables this enzyme in platelets, preventing clots, while ibuprofen only blocks it temporarily. If ibuprofen gets to the binding site first, it prevents aspirin from doing its job. Once the ibuprofen wears off, the aspirin has already been cleared from the body due to its short half-life. The net result is that your daily aspirin may not be protecting you the way it should.
Ibuprofen can also increase bleeding risk when combined with blood thinners, and it may reduce the effectiveness of certain blood pressure medications. If you take any daily medications, it’s worth checking whether ibuprofen is compatible before using it regularly.