Ibuprofen vs. Acetaminophen: What to Take When

These OTC pain relievers work in slightly different ways.

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The over-the-counter pain relievers often get clumped together, and unless your doctor has specifically told you to avoid one type, you might not actually know the difference between them—and what you should take when.

The two main players of over-the-counter pain relievers are often referred to as ibuprofen (e.g., Advil or Motrin) and acetaminophen (e.g., Tylenol), but it gets a little more complex than this.

Ibuprofen is just one type of nonsteroidal anti-inflammatory drug (NSAID), along with aspirin (e.g., Bayer) and naproxen (e.g., Aleve). Ibuprofen is the most common NSAID choice because it acts fast but doesn’t stay in the body too long, so it has a lower risk of long-term complications—but more on that later.

NSAIDs work by blocking enzymes in the body called cyclooxygenases, also known as COX enzymes. As part of the immune system's response to potential threats to health (like bacteria), these enzymes help form inflammatory substances in the body, which produce symptoms like pain, fever, and swelling. By inhibiting COX enzymes, NSAIDs can help reduce inflammation and pain.

Acetaminophen is not an anti-inflammatory drug, so it’s not as effective when the pain is being caused by inflammation. It’s not crystal clear *how* acetaminophen works, but the theory is that it somehow alters the way the body senses pain.

When to Take What

Ibuprofen and other NSAIDs are ideal if your pain is inflammation-based, which usually involves pain, swelling, redness, and stiffness. For example, it can help treat:

  • Fever

  • Muscle pain

  • Inflammatory arthritis

  • Menstrual pain

  • Symptoms of infections (e.g., sore throat and headache)

However, NSAIDs can have some long-term negative effects on the heart, digestive system, liver, and kidneys. This is usually harmless if you’re taking NSAIDs sporadically for the occasional fever, but it can be a little risky if you’re taking it regularly, such as for chronic pain. Additionally, ibuprofen should be avoided during pregnancy.

On the other hand, acetaminophen is useful for non-inflammatory pain, such as:

  • Osteoarthritis pain

  • Body aches

  • Fever

  • Mild headaches

Generally speaking, acetaminophen has fewer side effects than ibuprofen and other NSAIDs, and it may be recommended as the go-to pain reliever for people who cannot take ibuprofen. However, overuse of acetaminophen can damage the liver over time: That's because it exits the body via the liver. (Ibuprofen, on the other hand, exits the body through the kidneys.)

Acetaminophen may be safer during pregnancy compared to ibuprofen, but it’s recommended to consult a doctor before taking acetaminophen and any other OTC medications.

If you’re still not sure which pill to take for your aches and pains, talk to your doctor. The right choice may depend not only on your symptoms, but on your own unique medical history.