Aspirin vs. ibuprofen: Key differences and which to take - Insider

• Aspirin and ibuprofen contain different active ingredients — whereas aspirin is made with salicylic acid, ibuprofen is made with propionic acid. 
• However, both aspirin and ibuprofen can be used to treat pain caused by inflammation or injury, headaches, fevers, arthritis, and menstrual cramps.
• People at risk of cardiovascular disease may want to avoid ibuprofen, as it may increase your risk of heart troubles. 
• This article was medically reviewed by Jason R. McKnight, MD, MS, a family medicine physician and clinical assistant professor at Texas A&M College of Medicine. 

If you've taken an over-the-counter pain reliever before, you've likely had aspirin or ibuprofen. These are both very common nonsteroidal anti-inflammatory drugs, or NSAIDs, that are typically used to treat pain, inflammation, and fevers. 

They are popular active ingredients in various brand name products such as Advil and Motrin (ibuprofen) or Bayer and Ecotrin (aspirin). However, just because they are over-the-counter, it doesn't mean that they come without risks or are safe for everyone to use. 

Here's what you need to know about the difference between both medications.

The difference between aspirin and ibuprofen

While aspirin and ibuprofen are both NSAIDs, they are made from different key ingredients. 

Aspirin is made out of salicylic acid, and ibuprofen is made from propionic acid. The difference between the two acids is due to their chemical structures, particularly where the carbon and oxygen are located. 

Although they have slight chemical differences, aspirin and ibuprofen work in the same way. They both inhibit an enzyme called cyclooxygenase (also known as the COX enzyme). By doing this, they prevent the formation of prostaglandins, which are chemicals that cause inflammatory reactions. 

"When we inhibit those prostaglandins, we inhibit that inflammatory cascade of reactions which is what is causing pain. So, we eliminate the inflammation, or, reduce inflammation, and with it goes the pain as well," says Medhat Mikhael, MD, pain management specialist and medical director of the non-operative program at the Spine Health Center at MemorialCare Orange Coast Medical Center in Fountain Valley, California.

Also, the dosing of each medication is different. Aspirin typically comes in 325-milligram doses, whereas ibuprofen typically comes in 200-milligram doses. Both medicines can be taken every 4 to 6 hours, as needed for pain, fever, or other conditions. 

Which one should you take?

Both aspirin and ibuprofen are suited to treat pain and inflammation in the short term, over the course of a few days. They should not be used long term — consistently over the course of a few weeks or more — unless recommended by your doctor.

Mikhael says for some chronic pain conditions, ibuprofen may be taken long term during flare-ups, as long as they "interrupt" the doses and take a week or two off from the medication. Ibuprofen is more suitable than aspirin for longer-term use in situations like this.

Overall, Mikhael says they can both be used to treat the same problems, including:

One of the differences, though, is that aspirin can be used long term to prevent heart attack and stroke, Mikhael says. However, this is only when the aspirin is taken at a much lower dose of 81 milligrams. This is commonly referred to as baby aspirin. 

Your doctor may recommend that you take daily baby aspirin if you are at high risk for heart attack or stroke, like if you have very high blood pressure or have had a heart attack before.

Side effects of aspirin and ibuprofen

As with most medications, aspirin and ibuprofen both run the risk of side effects, including serious ones. Some potential side effects include:

• Abdominal pain
• Indigestion or heartburn
• Nausea
• Constipation
• Diarrhea
• Headache

Most commonly, Mikhael says somebody would experience the side effect of abdominal pain or heartburn, especially if they took the medication on an empty stomach. This is an indication that you might be dealing with gastritis or inflammation of the lining of the stomach. Aspirin is more likely to cause gastrointestinal side effects than ibuprofen.

Taking high doses of aspirin or ibuprofen long term can result in serious side effects such as peptic ulcers (ulcers in the stomach or small intestines) or kidney failure, Mikhael says. Your risk for peptic ulcers is higher with aspirin. 

But unlike aspirin, ibuprofen may increase your risk of cardiovascular problems. This is why it's so important to use medications as directed and only short term, not long term, to avoid these serious side effects.

Some people may need to avoid aspirin and ibuprofen together if they have certain conditions. Mikhael says the following groups of people may want to avoid aspirin due to the increased risk of related side effects:

• People at increased risk of bleeding
• People with a history of kidney problems
• People with a history of peptic ulcer disease or severe gastritis

The following groups of people may want to avoid ibuprofen due to the increased risk of related side effects: 

• People with a personal history or family history of cardiovascular disease
• People with a history of kidney problems
• People with a history of peptic ulcer disease or severe gastritis

Additionally, if you are pregnant you should not use either medication, Instead, Mikhael recommends opting for acetaminophen (Tylenol) if you need a pain reliever during pregnancy.

The bottom line

Whether you take aspirin or ibuprofen is mostly up to a personal preference, since they are indicated for use for the same ailments and they both risk serious side effects. If you aren't sure if these NSAIDs are right for you, check with your doctor before taking either one of them to be safe, and always take the medications as directed. 

Ashley Laderer