Both ibuprofen and acetaminophen (Tylenol) are commonly used over-the-counter pain medications. However, they have different mechanisms of action and side effect profiles. Determining which one is safer depends on several factors.
How ibuprofen and acetaminophen work
Ibuprofen is a nonsteroidal anti-inflammatory drug (NSAID) that works by blocking the production of prostaglandins, substances in the body that promote pain, fever and inflammation. By reducing prostaglandins, ibuprofen reduces pain, fever and inflammation.
In contrast, acetaminophen is not an NSAID. It works by inhibiting the synthesis of prostaglandins in the central nervous system, reducing pain and fever, but it has minimal anti-inflammatory effects. Acetaminophen is also thought to act indirectly on the cannabinoid receptors in the brain to reduce pain.
Pain relief differences
For mild to moderate pain, such as headaches, muscle aches or menstrual cramps, both ibuprofen and acetaminophen are effective. However, ibuprofen may have greater pain-relieving effects for certain types of pain because it reduces inflammation in addition to blocking pain signals.
For example, in people with osteoarthritis, rheumatoid arthritis or other inflammatory pain conditions, ibuprofen may provide better pain relief than acetaminophen. Ibuprofen is also more effective for reducing pain and swelling after surgery such as dental procedures.
Anti-inflammatory differences
One of the main differences between ibuprofen and acetaminophen is that ibuprofen has anti-inflammatory properties while acetaminophen does not. Ibuprofen can reduce inflammation from conditions like arthritis, muscle strains, sprains and dental pain.
Acetaminophen will not reduce inflammation so it may not be as effective for inflammatory pain conditions. However, acetaminophen may still provide pain relief by acting centrally on pain signaling pathways in the brain.
Fever reduction
Both ibuprofen and acetaminophen are considered equally effective antipyretic medications, meaning they reduce fevers. They both inhibit prostaglandin production in the hypothalamus, which regulates body temperature.
For treating a fever, there is no clear advantage of using one over the other. Either ibuprofen or acetaminophen can be used to reduce fever from viral infections like colds and flu.
Upset stomach and GI bleeding risks
One of the most common side effects of NSAIDs like ibuprofen is stomach upset, dyspepsia and nausea. Ibuprofen can cause these symptoms in up to 15% of people who take it.
This is because ibuprofen may irritate the lining of the stomach and small intestine, especially when taken for a long time. It can also increase the risk of ulcer formation in the GI tract and associated bleeding.
In contrast, acetaminophen has a lower rate of GI side effects than ibuprofen. Acetaminophen is not an NSAID so it does not irritate the GI tract as much. Only around 1-3% of people experience GI side effects from acetaminophen.
For people with sensitive stomachs or conditions like gastritis, ulcers or GI bleeding, acetaminophen may be the safer option over ibuprofen from a GI perspective.
Kidney toxicity
Both ibuprofen and acetaminophen are filtered through the kidneys so they can potentially cause kidney damage if taken excessively over time. However, the risks are not equal between the two drugs.
Acetaminophen is more likely to cause kidney toxicity than ibuprofen, especially at high doses or in people with existing kidney disease. Acetaminophen gets metabolized into compounds that can damage kidney tubule cells when taken in excess.
Ibuprofen can also impact kidney function by reducing blood flow to the kidneys. But normal doses of ibuprofen are not as nephrotoxic as acetaminophen overdoses can be.
Liver toxicity
Acetaminophen also carries a higher risk of liver toxicity than ibuprofen. At therapeutic doses acetaminophen is metabolized by the liver into nontoxic compounds.
But in overdose amounts, acetaminophen gets converted into a substance called NAPQI which can damage liver cells. Even at just slightly above the recommended dosage, NAPQI buildup can cause life-threatening liver toxicity.
Ibuprofen is not metabolized through the same pathway so it does not have the same liver toxicity effects. However, long-term high-dose ibuprofen use can still negatively impact liver function.
Blood clotting effects
Ibuprofen interferes with platelet aggregation and prolongs bleeding time. By keeping platelets from clumping together, ibuprofen may increase the risk of bruising and bleeding events.
This side effect is most concerning for people already on blood thinners or who have clotting disorders. However, even in healthy individuals ibuprofen can increase bleeding during surgery.
Acetaminophen does not carry these same clotting risks. Acetaminophen is generally considered safe for people prone to bleeding and does not increase bleeding risk during surgery.
Cardiovascular side effects
NSAIDs like ibuprofen have been associated with an increased risk of cardiovascular problems like heart attack and stroke, especially with long-term use. Ibuprofen can cause sodium and fluid retention, potentially raising blood pressure.
Acetaminophen is not linked to these cardiovascular side effects. For people at high risk for cardiovascular disease, acetaminophen may be a safer option than ibuprofen from a cardiac standpoint.
Allergy and asthma risks
Up to 15% of people with asthma are sensitive to NSAIDs like ibuprofen. Ibuprofen can trigger bronchospasm and asthma attacks in susceptible individuals.
Acetaminophen does not appear to increase bronchospasm or asthma exacerbations. People with asthma or nasal polyps are generally able to safely take acetaminophen without allergy issues.
Both ibuprofen and acetaminophen contain inactive ingredients that can cause allergic reactions in some people. But overall ibuprofen has a higher allergy risk.
Reye’s syndrome concerns
Reye’s syndrome is a rare but life-threatening condition that has been associated with taking aspirin or NSAIDs during viral infections like the flu or chickenpox. It involves swelling in the liver and brain that can rapidly progress.
Due to this risk, providers recommend avoiding aspirin and NSAIDs like ibuprofen in children with viral infections. Acetaminophen does not carry this same concern and can typically be used more safely in kids.
Drug interactions
Both ibuprofen and acetaminophen have drug interactions to be aware of.
Ibuprofen can interact with many medications including blood thinners, blood pressure drugs, diuretics, lithium, methotrexate, corticosteroids and more. Ibuprofen should not be combined with other NSAIDs due to increased bleeding risk.
Acetaminophen also interacts with some drugs. Most significantly, combining acetaminophen with alcohol increases the risk of liver toxicity. Acetaminophen can also interact with warfarin, certain epilepsy drugs and some antibiotics.
Always read medication labels carefully and consult a pharmacist when combining other medications with ibuprofen or acetaminophen.
Overdose potential
Both ibuprofen and acetaminophen can be toxic when taken in excessive amounts, but acetaminophen overdose is significantly more dangerous.
Ibuprofen overdose can cause GI bleeding, kidney damage and metabolic acidosis. However, serious toxicity generally only occurs at extremely high doses over several grams.
In contrast, acetaminophen toxicity can occur when exceeding the maximum recommended dose of 4,000 mg per day in adults. Just 7,000-10,000 mg per day can cause liver failure and death. Acetaminophen overdoses require urgent medical treatment to prevent mortality.
Popularity
Acetaminophen and ibuprofen are two of the most commonly used medications in the United States:
- Acetaminophen is the active ingredient in over 600 different generic and brand name medications, including Tylenol.
- Ibuprofen is the active ingredient in over 400 different generic and brand name medications, including Advil and Motrin.
- Each year, nearly 27 billion doses of acetaminophen are sold in the U.S. compared to 15 billion doses of ibuprofen.
- A nationwide survey found that 17% of US adults had used an acetaminophen product and 15% had used an ibuprofen product in the previous week.
While acetaminophen may have higher use rates, this does not necessarily mean it is the safer option. Use should be based on each individual’s medical history and health status.
Costs
Both ibuprofen and acetaminophen are available as low-cost generic medications. On average:
- Generic ibuprofen costs around $0.04 per 200mg tablet.
- Generic acetaminophen costs around $0.03 per 500mg tablet.
- Brand name ibuprofen like Advil costs around $0.40 per 200mg tablet.
- Brand name acetaminophen like Tylenol costs around $0.25 per 500mg tablet.
Due to widespread availability of generics, ibuprofen and acetaminophen are two of the least expensive over-the-counter pain relievers.
Safety during pregnancy
For pregnant women needing pain or fever management, acetaminophen is generally preferred over ibuprofen:
- Acetaminophen has not been shown to cause harm to the fetus when used as directed.
- Ibuprofen may increase the risk for miscarriage or certain birth defects if used in the first and second trimesters.
- Both drugs should only be used conservatively as needed during pregnancy.
Safety for children
For short-term use in children, both ibuprofen and acetaminophen are considered relatively safe. However, acetaminophen is typically the first-line recommendation:
- When given appropriate child-dosed amounts, acetaminophen is effective for pain and fever reduction in infants over 2-3 months old.
- Ibuprofen can be used for short periods in children over 6 months but has more drug interactions.
- In young children with viral infections, acetaminophen is recommended over ibuprofen due to Reye’s syndrome concerns.
Long-term safety
For long-term daily pain management, acetaminophen may be safer than ibuprofen:
- Regular daily ibuprofen use can increase the risks of GI bleeding, kidney dysfunction, heart disease and hypertension over time.
- Acetaminophen has fewer systemic side effects with chronic regular use.
- However, long-term acetaminophen use still has risks including liver and kidney damage at high doses.
Neither medication should be taken continually for extended periods without medical supervision. Short-term use as needed is recommended for both drugs.
Conclusion
In general, acetaminophen has a better overall safety profile and is less likely to cause serious side effects than ibuprofen. However, ibuprofen is a more potent anti-inflammatory and can relieve certain types of pain more effectively.
For people with no underlying health conditions, both drugs are considered relatively safe when used properly at recommended dosages. However, each medication has risks to be aware of.
Consult a doctor or pharmacist about which option is right for your individual health status and type of pain being treated. Use the lowest effective dose of either medication for the shortest duration needed to balance pain relief with safety.