Acetaminophen vs. ibuprofen – how to know what medication to take safely
- Category: General, Pain Management, Primary Care, Maternity Care
- Posted On:
- Written By: Boulder Community Health
As we approach respiratory season, it’s important to know how to manage the symptoms of illness to get better quickly and avoid an unnecessary trip to the hospital. Symptoms like fever, chills, aches, nasal congestion, coughing and sneezing are all commonly experienced this time of year – so what over-the-counter (OTC) medications are available to help manage these symptoms, and how do you know which to take?
Two of the most common medications to manage symptoms of respiratory illness are acetaminophen (Tylenol) and ibuprofen (Advil or Motrin, etc.). These two medications are used in hundreds of OTC medications, many of which use a combination of other medications to treat specific sets of symptoms for conditions such as cold and flu, but also can be used for menstrual cramps, pain or swelling from injury, headaches and migraines, and even in sleep aids.
How do acetaminophen and ibuprofen work?
Ibuprofen, also known as Nonsteroidal anti-inflammatory drugs (NSAID) and acetaminophen both work by blocking or reducing the activity of enzymes called cyclooxygenase (COX) in the body’s central nervous system. These enzymes are released due to tissue damage or illness, such as a sprained ankle or a surgical incision or respiratory infection. This reduction in COX enzyme pathways may prevent the release of some prostaglandins – fatty acids similar to hormones that are responsible for fever, inflammation and pain.
So, what does that mean? Essentially, ibuprofen and acetaminophen block the messengers in our body that tell our brain to create fever and pain.
What is the difference between acetaminophen and ibuprofen?
Ibuprofen (NSAIDs) blocks the enzymes responsible for fever, pain and inflammation.
Acetaminophen only blocks the enzymes responsible for fever and pain.
That means ibuprofen is a better option when you are trying to control or reduce swelling. If you don’t need to control or reduce swelling, acetaminophen may be the better option to avoid negative side effects.
Side effects and risks of acetaminophen and ibuprofen
Ibuprofen in some cases can cause gastrointestinal distress such as stomach pain, nausea and stomach ulcers. Large doses can even cause poor kidney function, fluid retention and high blood pressure – especially for people with preexisting conditions.
Acetaminophen is generally safer than other pain medications, however, it’s important to only take the dose recommended by your health care provider. Taking more than is recommended can increase risk of kidney failure and liver damage, especially if taken with alcohol.
Use of acetaminophen and ibuprofen use in pregnancy
For patients who are pregnant or considering becoming pregnant, it’s important to know how to manage fever, as fever poses significant risks to a developing fetus. According to ACOG, “Fever during pregnancy increases the risk of neural tube defects (NTDs) and other birth defects. Untreated pain can increase stress hormones and affect the body in other ways, all of which can negatively affect a fetus.”
Ibuprofen is not recommended in pregnancy. ACOG states, “If you are pregnant, you should not take ibuprofen or naproxen unless recommended by your ob-gyn. It’s not clear if ibuprofen and naproxen are safe for a fetus during the first trimester. Taking them during the third trimester may lead to birth defects.”
Acetaminophen is recommended as a safe medication for fever and pain relief in pregnancy.
The American College of Obstetrics and Gynecology (ACOG) states, “You may have heard claims about acetaminophen being linked to autism or attention-deficit/hyperactivity disorder (ADHD). This has not been proven by science.”
ACOG iterates “The two highest-quality studies on the topic — Gustavson et al. 2021 and Ahlqvist et al. 2024 — represent the most reassuring and clinically useful evidence we have to date that acetaminophen use in pregnancy is safe.“ This position is shared by the American Pharmacists Association (APhA).
These two studies “found no significant associations between use of acetaminophen during pregnancy and children’s risk of autism, ADHD, or intellectual disability.”
One article states, “Acetaminophen use during pregnancy was not associated with children’s risk of autism, ADHD, or intellectual disability in sibling control analysis. This suggests that associations observed in other models may have been attributable to familial confounding… Multiple biases may explain the associations observed in previous studies between acetaminophen use and neurodevelopmental disorders.”
To learn more, see ACOG’s frequently asked questions on acetaminophen in pregnancy.
The most important consideration for all patients when deciding whether to take acetaminophen or ibuprofen is to talk with your doctor or advance practice provider (APP). Each person’s health status, health history and lifestyle play an important role in what medication, and how much of it, are safe to take.
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Sources: https://www.ncbi.nlm.nih.gov/books/NBK482369/
https://www.acog.org/news/news-releases/2025/09/acog-affirms-safety-benefits-acetaminophen-pregnancy
https://www.acog.org/womens-health/faqs/acetaminophen-and-pregnancy