Motrin IB is an over-the-counter pain reliever and fever reducer. Its active ingredient is ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID), and each tablet contains 200 mg. The “IB” stands for “ibuprofen,” distinguishing the OTC product from prescription-strength Motrin, which comes in 400 mg, 600 mg, and 800 mg tablets.
What Motrin IB Treats
Motrin IB is approved for temporary relief of minor aches and pains from headaches, muscle soreness, backaches, toothaches, menstrual cramps, the common cold, and minor arthritis pain. It also reduces fever. These are the same uses as Advil, which contains the same active ingredient at the same dose.
How It Works
When you’re in pain or running a fever, your body produces chemical messengers called prostaglandins that amplify inflammation, pain signals, and body temperature. Ibuprofen blocks the enzyme responsible for making these prostaglandins, which is why it tackles pain, swelling, and fever all at once. This is a key difference from acetaminophen (Tylenol), which relieves pain and reduces fever but does not reduce inflammation.
Ibuprofen works as a competitive inhibitor, meaning it physically occupies the spot in the enzyme where the raw material for prostaglandin production would normally go. This effect is reversible: once the drug clears your system, the enzyme resumes normal activity.
How Fast It Works and How Long It Lasts
Taken by mouth, ibuprofen typically kicks in within 30 to 60 minutes. A single dose provides relief for roughly 6 to 8 hours, though pain severity and individual metabolism can shift that window. For comparison, acetaminophen tends to wear off faster, while naproxen (Aleve) lasts longer but takes a similar amount of time to start working.
Dosing for Adults
The standard OTC dose for mild to moderate pain is 200 to 400 mg every four to six hours as needed. For menstrual cramps specifically, 400 mg every four hours is a common recommendation. The maximum OTC daily dose is typically 1,200 mg (six 200 mg tablets) unless directed otherwise by a doctor. Prescription doses for conditions like rheumatoid arthritis can go significantly higher, up to 3,200 mg per day, but that requires medical supervision.
You should take ibuprofen with food or milk. Taking it on an empty stomach increases the chance of stomach irritation.
Motrin IB vs. Advil vs. Tylenol vs. Aleve
Motrin IB and Advil are the same drug at the same strength. They’re both 200 mg ibuprofen tablets, and choosing between them is purely a brand preference.
- Tylenol (acetaminophen): Relieves pain and fever but does not reduce inflammation. It’s easier on the stomach and kidneys, making it a better option for people with GI or kidney issues. It can be given to infants and used right up until surgery. However, it can damage the liver at high doses or with alcohol use.
- Aleve (naproxen): Another NSAID with anti-inflammatory effects, but longer lasting. You typically only need two doses per day. Like ibuprofen, it should be taken with food and avoided before surgery (stop at least 72 hours prior). It carries similar stomach and kidney risks.
- Motrin IB / Advil (ibuprofen): Falls between the two in terms of duration. It reduces inflammation, unlike Tylenol, but needs more frequent dosing than Aleve. Should not be used in infants under six months old, and it should also be stopped 72 hours before surgery.
Side Effects and Risks
The same enzyme ibuprofen blocks to reduce pain also plays a role in protecting your stomach lining, maintaining kidney blood flow, and supporting normal blood clotting. That’s why the most common side effects involve the gut: stomach pain, nausea, and heartburn. Taking it with food helps, but long-term or high-dose use raises the risk of stomach ulcers and bleeding.
Kidney problems from ibuprofen are uncommon but real. Research has shown that doses above 1,200 mg per day increase the risk of acute kidney injury, and daily use for more than a year raises the risk of chronic kidney disease. People with high blood pressure, older adults, and anyone already on medications that affect kidney function face higher risk. Ibuprofen can also cause the body to retain sodium and fluid, which may worsen existing high blood pressure.
Who Should Avoid Motrin IB
If you take a blood thinner like warfarin, ibuprofen can increase your risk of serious bleeding. The interaction is well documented and requires caution, especially if you’re on a higher warfarin dose or taking other medications that affect clotting.
Pregnant women should avoid ibuprofen from 20 weeks of pregnancy onward. The FDA issued guidance that NSAIDs used at 20 weeks or later can cause rare but serious kidney problems in the developing baby, leading to dangerously low amniotic fluid levels. After 30 weeks, use is strongly discouraged entirely.
You should also avoid combining Motrin IB with other NSAIDs like aspirin or naproxen. Stacking NSAIDs doesn’t improve pain relief but does multiply the risk of stomach bleeding and kidney damage. People with existing GI conditions, kidney disease, or a history of stomach ulcers are generally better off with acetaminophen for routine pain management.