What's the Difference Between Aspirin, Ibuprofen and Acetaminophen?

By: Alia Hoyt
OTC headache remedies
A collection of over-the-counter headache pain medications line the shelves of a CVS Pharmacy. But what's the difference between them? Jeffrey Greenberg/Universal Images Group via Getty Images

The average headache or backache often sends people reaching willy-nilly for the nearest bottle of pain reliever, but for best results it's smart to match the particular problem with the perfect pill. That's because the wide variety of pain relievers (known in medical circles as analgesics) available today are each effective at different problems and come with different risks.

There are two categories of pain pills suitable for home use — nonsteroidal anti-inflammatory drugs, more commonly referred to as NSAIDs, and acetaminophen. Both also are considered antipyretics, which means that they can reduce fevers.


Most people know acetaminophen better by the popular brand name Tylenol, but there are other brands as well (like FeverAll). The category of NSAIDs is broader, as aspirin, ibuprofen and naproxen all fall under the umbrella (there are others, but these three are some of the most widely used). Each has its own range of brand names associated with it.

So, which one is best to use? It all depends on what you're taking it for. We'll clue you in on all these pain relievers below:



Brand name: Tylenol

What it is: Acetaminophen was approved by the U.S. Food and Drug Administration in 1951, but how it works is still not clearly understood. Nevertheless, certain facts have been worked out over the years. "Acetaminophen does not decrease inflammation, but works in the hypothalamus to reduce fever," explains pharmacist Tara Thompson, Pharm.D., V.P. of clinical services at Innovation Compounding in an email interview. Additionally, "it may work peripherally to block the generation of pain."


When to take it: "Those with fever, flu-like pain symptoms, or pain from headaches may benefit from taking acetaminophen," Thompson says. It also can help with the pain from inflammatory diseases like arthritis and menstrual cramps but note: It'll only mask the pain without treating the underlying inflammation problem.

When NOT to take it: Acetaminophen should never be taken while consuming alcohol. It can be hard on the liver even when stone-cold sober, and much worse when consuming alcohol.

Most serious liver problems have been reported following large doses (the highest amount that's considered safe is 3,250 milligrams per day or 10 regular-strength tablets.) However, there have been instances when liver damage occurs after medicating with moderate or even small doses over a long time.

Acetaminophen should be taken carefully in conjunction with other medications, as many headache and cold meds (like Nyquil) already have the analgesic in them. This can lead to accidental overdoses. Anyone taking one of these "extras" should carefully read labels and follow dosing instructions to the letter.

Acetaminophen is considered safe enough to take by just about everyone, but occasionally side effects are experienced. Most often, those are nausea, rash and headache, which is ironic since many people take it to treat the latter!



Brand names: Bayer, Advil, Motrin, Aleve

What they are: You know how acetaminophen doesn't do a darn thing to reduce inflammation? Well, NSAIDs pick up that dropped ball and run all the way into the endzone with it. Short for nonsteroidal anti-inflammatory drugs, the category of NSAIDs include a variety of analgesics, like aspirin (one brand name is Bayer), ibuprofen (Advil, Motrin) and naproxen (Aleve). Although there's some variation by particular type, NSAIDs in general treat inflammation by blocking the production of chemicals called prostaglandins, which encourage fever, pain and inflammation. Incidentally, steroidal meds also reduce inflammation, which is why this category goes out of its way to denote "nonsteroidal" in the name because it's a major distinction.


When to take them: "NSAIDs such as aspirin, ibuprofen, and naproxen have specific mechanisms of action in the body which decrease inflammation, so those with inflammatory conditions such as osteoarthritis, rheumatoid arthritis, menstrual pain, or muscular pain would benefit from an NSAID," Thompson notes. "Naproxen tends to work longer in the body (about two times longer!), so those with gout or more chronic pain conditions may see more pain relief from using naproxen versus ibuprofen." However, ibuprofen provides quicker relief than naproxen and is less likely to cause an upset stomach, so might be more appropriate for acute pain.

Aspirin has long been used as a daily supplement of sorts for people at risk of heart attack and stroke because it inhibits potentially tragic blood clotting for roughly four to seven days. One important caveat, however, is that people consuming aspirin for that purpose should use a lower dosage aspiring (under 325 milligrams per day) than those using it for pain relief purposes. Thompson says that aspirin is more commonly used nowadays for inhibiting blood clotting than for relieving pain, due to intestinal bleeding risks, which brings us to...

When NOT to take them: Women who are pregnant or trying to become pregnant are typically advised to avoid use of NSAIDs because they are believed to cause fertility issues, early miscarriage and even birth defects. In particular, they should not be taken in the third trimester because they could cause premature closure of the ductus arteriosus (a blood vessel in the developing baby).

People with gastrointestinal problems might also steer clear of NSAID use. "NSAIDS are known for their potential negative GI side effects, which can include ulcers or intestinal bleeding," Thompson says. This occurs because prostaglandins, those fever- and inflammation-encouraging chemicals that are wrecked by NSAIDs, aren't all bad. In fact, prostaglandins protect the stomach lining and help with blood clotting. When those functions are inhibited, the risk of bleeding and ulcers goes way up.

"Although this is more likely in those who take large doses for long periods of time, patients often turn to acetaminophen [from NSAIDs] for pain relief, since it does not cause intestinal issues," says Thompson.

Still confused about which to take? "Your local pharmacist at any retail pharmacy can help recommend the best medication and dose to take for your particular condition, and can help you find the right product on the shelf," she adds.