Acetaminophen

Acetaminophen is used across many oral and injectable products to relieve pain and reduce fever. Supported uses include:

• Headache
• Minor aches and pains from the common cold
• Backache
• Muscle aches
• Minor pain of arthritis
• Toothache
• Premenstrual and menstrual cramps
• Sore throat pain (noted in Robitussin Direct Sore Throat Pain oral tablets)
• Temporary reduction of fever
• The intravenous injection form is used in clinical settings to treat acute pain in adults and pediatric patients 2 years and older, and to reduce fever in adults and pediatric patients including premature neonates born at ≥32 weeks gestational age

Acetaminophen relieves pain and lowers fever, but its exact mechanism isn't fully understood. Researchers believe it works primarily through actions in the central nervous system — the brain and spinal cord — rather than by reducing inflammation at the injury site the way NSAIDs like ibuprofen do. It does not significantly affect platelet function (the blood cells involved in clotting) at normal doses.

Acetaminophen comes in many oral forms — tablets, capsules, liquids, chewable tablets, and powders — taken by mouth, as well as an intravenous (IV) injection given by healthcare providers. Oral doses are typically repeated every 4 to 6 hours while symptoms last. The IV injection form is infused over 15 minutes in a clinical setting.

• Never exceed the maximum daily dose listed on your product's label
• Do not take two acetaminophen-containing products at the same time
• For oral liquid products designed for children (such as MAX relief junior), always use the measuring device included in the package
• Follow your prescriber's or pharmacist's specific instructions — do not adjust your dose on your own

Most people tolerate acetaminophen well, but some side effects can occur. The most common ones reported in clinical trials with the IV form include:

• Nausea
• Vomiting
• Headache
• Insomnia (trouble sleeping) — in adults
• Constipation — in children receiving IV form
• Itching (pruritus) — in children receiving IV form
• Fatigue
• Anemia (low red blood cell count)

Serious reactions — including liver damage, life-threatening skin reactions, and severe allergic responses — are rare but require immediate medical attention. Stop use and seek help right away if you notice a skin rash, blistering, facial swelling, difficulty breathing, or signs of liver trouble such as yellowing of the skin or eyes.

• Liver damage is the most serious risk. Taking more than the maximum daily dose — or combining multiple products that contain acetaminophen — can cause acute liver failure, which can be fatal or require a liver transplant. People with liver disease, heavy alcohol use, malnutrition, or severe dehydration are at higher risk.
• Serious skin reactions, including Stevens-Johnson Syndrome (a severe blistering skin condition) and toxic epidermal necrolysis, have been reported rarely. Stop use immediately at the first sign of a skin rash.
• Severe allergic reactions (anaphylaxis), including throat swelling and breathing difficulty, have been reported. Do not use if you are allergic to acetaminophen.
• For the IV injection form, dosing errors — confusing milligrams with milliliters, or miscalculating weight-based doses — have caused accidental overdose and death. This form must be used only by trained healthcare providers.
• Stop use and contact a doctor if pain lasts more than 10 days, fever lasts more than 3 days, or new symptoms such as redness or swelling develop.

Acetaminophen has a few important interactions to know about:

• Warfarin (Coumadin) — Regular daily use of acetaminophen can increase INR levels (a measure of blood clotting time) in people stabilized on warfarin, raising the risk of bleeding. More frequent monitoring may be needed.
• Alcohol — Drinking 3 or more alcoholic drinks per day while taking acetaminophen significantly increases the risk of liver damage. Alcohol can also alter how the liver processes acetaminophen.
• Other acetaminophen-containing products — Combining prescription or OTC products that both contain acetaminophen can push your total daily dose over the safe limit. Always read ingredient labels carefully.
• Substances affecting CYP2E1 — Drugs or chemicals that affect this liver enzyme can change how acetaminophen is broken down, potentially increasing its liver toxicity risk.

This is not a complete list of interactions. Always talk with your doctor or pharmacist before starting, stopping, or changing any medication.

• Do not use if you have a known allergy to acetaminophen or to any inactive ingredients in the product
• Do not use if you have severe liver disease or severe active liver disease — acetaminophen is contraindicated in these situations
• Use with caution if you have any degree of liver impairment or active liver disease — a lower total daily dose may be needed
• Use with caution if you have severe kidney disease (creatinine clearance ≤ 30 mL/min) — longer intervals between doses and a lower total daily dose may be needed
• Use with caution if you drink heavily, are chronically malnourished, or are severely dehydrated
• Tell your doctor if you take warfarin or any other blood thinner
• If you are pregnant, published studies have not shown a clear link between acetaminophen and birth defects, but animal studies have raised some concerns at higher doses — ask your doctor before use
• Acetaminophen passes into breast milk; if you are breastfeeding, discuss use with your healthcare provider
• Animal studies suggest acetaminophen may affect fertility in males and females — discuss with your doctor if relevant
• For children: the IV injection form's effectiveness for acute pain has not been established in children under 2 years of age
• Older adults: no overall differences in safety have been identified, but greater sensitivity in some individuals cannot be ruled out

Taking too much acetaminophen can cause severe and potentially fatal liver damage (hepatic necrosis). Early overdose symptoms include nausea, vomiting, sweating, and a general feeling of illness — but liver damage may not show up on lab tests for 48 to 72 hours, so do not wait for symptoms to worsen. If an overdose is suspected, call Poison Control immediately at 1-800-222-1222 or go to the nearest emergency room — quick treatment with the antidote N-acetylcysteine (NAC) can be life-saving.

Acetaminophen has both pain-relieving (analgesic) and fever-reducing (antipyretic) effects, confirmed in human and animal studies. At normal therapeutic doses, it does not significantly affect platelet aggregation (the clumping of blood cells that causes clotting), and it does not affect blood vessel hemostasis (the process that stops bleeding). This is an important distinction from NSAIDs like ibuprofen or aspirin.

When given by IV infusion over 15 minutes, acetaminophen reaches its peak blood concentration at the end of the infusion — and that peak is up to 70% higher than the same dose taken orally, although the overall total amount absorbed (AUC) is very similar between the two routes. The drug distributes widely throughout most body tissues except fat, and very little (10–25%) binds to proteins in the blood. Acetaminophen is broken down primarily in the liver into several metabolites; at normal doses, a reactive byproduct called NAPQI is quickly neutralized by a natural antioxidant called glutathione. More than 90% of a dose leaves the body in the urine within 24 hours, with a half-life (the time for blood levels to fall by half) of roughly 2 to 3 hours in most patients.

store between 20-25°C (68-77°F). Protect from light. store between 20-25°C (68-77°F) do not use if carton is opened.