Acetaminophen and Blood in Stool: What to Know

Yes, blood in stool can occur with acetaminophen, but it appears to be rare and warrants immediate medical attention. ^[1] Official patient guidance lists “bloody or black, tarry stools” among side effects that need prompt medical evaluation when taking acetaminophen. ^[2] Instructions for over-the-counter labeling also advise to stop use and consult a doctor if you notice bloody or black stools, faintness, vomiting blood, or stomach pain that doesn’t improve. ^[3]

How common is this?

Serious gastrointestinal (GI) bleeding with acetaminophen at typical over‑the‑counter doses seems uncommon compared with non‑steroidal anti‑inflammatory drugs (NSAIDs). [PM13] Reviews suggest acetaminophen generally has better GI tolerability than NSAIDs, with a low risk of ulcers or upper GI bleeding at standard doses. [PM15] That said, rare adverse events can still happen, and any sign of GI bleeding should be treated urgently. ^[2]

Why can bleeding happen?

Most GI bleeding risk is classically linked to NSAIDs, not acetaminophen, but acetaminophen can be associated with unusual bleeding signs in rare cases. [PM13] Acetaminophen does not routinely inhibit platelets like aspirin, yet rare immune reactions affecting platelets (drug‑induced thrombocytopenia) have been described with acetaminophen metabolites, which could theoretically increase bleeding tendency. [PM18] Alcohol use, combined products with NSAIDs, or concurrent blood thinners can also shift the risk profile, making bleeding more likely from the stomach or intestines. ^{[4] [5]}

Warning signs to act on

• Black, tarry stools or visible red blood in stool (melena or hematochezia). ^[2]
• Stomach pain that does not get better, vomiting blood, or feeling faint. ^[3]
• Unusual bleeding or bruising, sore throat or fever not present before treatment, or pinpoint red spots on the skin. ^[2]
• Yellowing of the skin/eyes, dark urine, pale stools, upper abdominal pain these can signal liver injury, which also requires urgent care. ^[6]

If you notice any of the above, stop acetaminophen and seek medical care right away. ^[2] Serious overdose symptoms (nausea, vomiting, abdominal pain, sweating) also require emergency help even if you feel well, because early treatment prevents liver damage. ^{[7] [8]}

Who is at higher risk?

You’re at higher risk of stomach or bowel bleeding if you are over 60, drink alcohol regularly, have had ulcers or bleeding before, smoke, or take certain medicines (NSAIDs, steroids, or blood thinners). ^[9] Combination products that include both ibuprofen (an NSAID) and acetaminophen carry specific stomach bleeding warnings. ^[10] Even acetaminophen‑only labels advise stopping and asking a doctor if signs of stomach bleeding occur. ^[3]

Safe use tips

Use the lowest effective dose and avoid exceeding 4,000 mg of acetaminophen in 24 hours. ^[11] Do not take more than one product containing acetaminophen (often labeled “APAP”) at the same time, as this increases risk of overdose and liver injury. ^[12] If you need more than occasional use, avoid alcohol, as it can increase liver risk and complicate bleeding. ^[6]

Special caution with blood thinners

Chronic acetaminophen at 4,000 mg/day can increase INR in some people on warfarin, potentially raising bleeding risk; monitoring and dose adjustments may be needed. ^[13] This interaction has been observed across multiple acetaminophen products at the same daily dose. ^[14] Short‑term use may be safer, but dedicated studies are limited, so discuss with your clinician if you take warfarin or similar anticoagulants. ^{[15] [16] [17] [18]}

What to do if you see blood in your stool

1. Stop acetaminophen and seek urgent medical care to evaluate and treat possible GI bleeding. ^[2] 2) Bring a list of all medicines, including combination cold/flu products, to check for hidden acetaminophen or NSAIDs. ^[12] 3) Avoid alcohol and any NSAIDs (like ibuprofen, naproxen, aspirin) until a clinician advises otherwise, as these can worsen bleeding. ^[9] 4) If you’re on warfarin or other blood thinners, arrange prompt INR or coagulation checks per your clinician’s guidance. ^[13]

Alternatives and coping strategies

If bleeding is confirmed or strongly suspected, acetaminophen and NSAIDs should generally be avoided until a clinician determines the cause and stabilizes you. ^[9] For future pain management, options may include adjusted acetaminophen dosing under supervision, non‑drug measures (rest, ice/heat, physical therapy), or other medications chosen to minimize GI risk. [PM13] Your clinician may also review ulcer prevention strategies if pain medicines are needed, and screen for contributing factors like alcohol use or prior GI disease. [PM13]

Bottom line

Blood in stool with acetaminophen is rare but serious; stop the drug and seek medical care immediately if it happens. ^[2] Acetaminophen is typically gentler on the stomach than NSAIDs, yet risks rise with overdose, alcohol, certain combinations, and anticoagulant use. [PM13] ^[13] Careful label checking, dosing within 4,000 mg/day, and avoiding multiple acetaminophen products help reduce harm. ^{[11] [12]}