Acephen Dosage: 4 Suppository Strengths, 4 Different Age Charts

Quick Answer: Acephen is a brand of acetaminophen rectal suppository, listed by the National Library of Medicine in 120 mg, 325 mg and 650 mg strengths. Over-the-counter acetaminophen suppositories as a group come in 80, 120, 325 and 650 mg, and the dose depends on which strength is in your box: each label carries its own age chart. On the current labels, the 650 mg suppository is for “adults and children 12 years and older: 1 suppository every 4 to 6 hours while symptoms last” and “do not exceed 6 suppositories in any 24 hour period”. The 120 mg suppository is for children 3 to 6 years, 1 every 4 to 6 hours, “maximum of 5 doses in 24 hours”, and under 3 years “Do not use unless directed by a doctor”. The 80 mg (infants’) suppository covers 6 months to 36 months. Suppository labels go by age, while the American Academy of Pediatrics chart for liquid acetaminophen goes by weight. We do not link to any product on this page.

People search for “Acephen dosage” because the suppository is usually handed over when a child is vomiting and cannot keep a liquid down, or by a nurse after surgery, and the box is not always in your hand. The trouble is that the same brand name covers suppositories that differ eight-fold in strength, from 80 mg to 650 mg across the over-the-counter range, and each strength has different directions. This page sets the four label charts side by side, quotes them exactly, and explains how they differ from the weight-based chart for liquid acetaminophen.

What Acephen is, and where its label is

Acephen is acetaminophen (the same drug as Tylenol) in a rectal suppository. RxNorm, the National Library of Medicine’s drug naming system, lists three Acephen products: acetaminophen 120 mg, 325 mg and 650 mg rectal suppositories. On DailyMed, the library’s label database, the only Acephen entry (checked 13 October 2026) is a 2016 box label for a 325 mg suppository repackaged by a community health centre, made by G&W Labs, and it carries no directions text. So the directions below are taken from the current over-the-counter acetaminophen suppository labels on DailyMed in each strength. They share the same active ingredient and strength; check that the milligrams on your box match the row you are reading.

The acetaminophen suppository dosing chart, from the labels

Every dose, interval and limit below is copied from the current Drug Facts labels (checked 13 October 2026). Where the label states an age group as “do not use” or “ask a doctor”, that wording is quoted.

The 80 mg and 120 mg labels both state: “this product does not contain directions or warnings for adult use.”

Why the box matters more than the brand

The same child can be inside the directions on one box and outside them on another. A two-year-old falls in the “12 to 36 months” row of the 80 mg infants’ label, which says “Use 1 suppository every 4 to 6 hours”. The 120 mg label, for the same child, says “under 3 years Do not use unless directed by a doctor”. The 325 mg label says “under 6 years do not use”, and the 650 mg label says “Do not use in children under 12 years”.

That is the practical reason to read the milligrams on the box before the brand name. “Acephen”, “FeverAll” and store brands are all sold in more than one strength, and the strength decides which age chart applies. The strengths also differ more than the sizes look: the largest over-the-counter suppository, 650 mg, holds eight times the acetaminophen of the 80 mg infants’ suppository.

Suppositories go by age; the liquid chart goes by weight

The suppository labels above give doses by age only. The chart most parents know for liquid acetaminophen, from the American Academy of Pediatrics, gives doses by weight first, and we set it out in our infant Tylenol dosage by weight page. The two are not interchangeable: a suppository cannot be split into a weight-based dose at home, and none of the labels above says it can. If your child is small or large for their age, or under the youngest age on your box, the labels’ own instruction is to use the product only as a doctor directs.

How suppositories are absorbed

A suppository has to dissolve before the drug can be absorbed, and studies in hospital settings have found the resulting blood levels vary. In a 1997 study of 28 children given rectal acetaminophen during surgery, most “did not achieve peak or sustained serum values in the 10-20 microg/ml serum concentration range associated with antipyresis” at the doses then recommended, and the authors’ models suggested absorption “is a function of zero-order dissolution of suppositories and first-order absorption from the rectum” (Birmingham 1997). The authors went on to recommend a larger first dose, but that was for children under anaesthesia and monitoring, and it is not what the over-the-counter labels say; follow the box.

In a small 2012 study in six healthy men comparing intravenous, oral and rectal acetaminophen, the “absorption phase, variability in plasma, and CSF were greater in PO and PR groups than variability with IV administration” (Singla 2012). In 40 infants after craniofacial surgery given oral or rectal acetaminophen, 9 (22.5%) did not reach the expected analgesic plasma levels, across both routes (van der Marel 2001). None of these studies changes the label directions; they explain why a suppository can seem to work less predictably than a liquid.

The adult 24-hour limit is higher than Extra Strength Tylenol’s

For adults and children 12 and older, both the 650 mg label (“do not exceed 6 suppositories in any 24 hour period”) and the 325 mg label (“Use 2 suppositories every 4 to 6 hours”, “maximum of 6 doses”) stop at six doses of 650 mg, which is 3,900 mg (six times 650 mg; the labels state the count, not the milligram total). That is the same total as the 8 HR Arthritis Pain caplet label and higher than the 3,000 mg that the Extra Strength Tylenol label works out to, as we set out in our adult Tylenol dosage page. Every one of these totals counts acetaminophen from all sources.

Never combine it with other acetaminophen

Each label says: “Do not use with any other drug containing acetaminophen (prescription or nonprescription). If you are not sure whether a drug contains acetaminophen, ask a doctor or pharmacist.” A suppository given because a child is vomiting, on top of a liquid dose given earlier, counts toward the same daily limit.

The liver warning on the 80 mg label reads: “Severe liver damage may occur if your child takes more than 4 doses in 24 hours, which is the maximum daily amount for ages 6 to 11 months”, “more than 5 doses in 24 hours, which is the maximum daily amount for ages 12 to 36 months”, and “with other drugs containing acetaminophen”. The 650 mg label adds, for adults: “an adult takes 3 or more alcoholic drinks every day while using this product”.

Liver disease, warfarin and skin reactions

The adult label says: “Ask a doctor before use if you have liver disease” or “you are taking the blood thinning drug warfarin”. The infants’ label puts it as “the child has liver disease” or “the child is taking the blood thinning drug warfarin”.

All of the labels carry the allergy alert: “acetaminophen may cause severe skin reactions”, with symptoms listed as skin reddening, blisters and rash: “If a skin reaction occurs, stop use and seek medical help right away.”

When to stop and call a doctor

The labels say to stop use and ask a doctor if “fever lasts more than 3 days (72 hours), or recurs”, if “new symptoms occur”, or if “redness or swelling is present in the painful area”. For pain, the infants’ label says “pain lasts more than 3 days or gets worse”; the 650 mg label says “pain gets worse or lasts more than 10 days”. In case of overdose: “get medical help or contact a Poison Control Center right away” (1-800-222-1222), and “Quick medical attention is critical in case of overdose for adults and for children even if you do not notice any signs or symptoms.”

Frequently Asked Questions

What is the Acephen dosage for adults?

For the 650 mg suppository, the label says adults and children 12 years and older use “1 suppository every 4 to 6 hours while symptoms last” and “do not exceed 6 suppositories in any 24 hour period”. For the 325 mg strength, the adult line is “Use 2 suppositories every 4 to 6 hours” with a “maximum of 6 doses”.

What is the Acephen 120 mg dosage for children?

The 120 mg label covers children 3 to 6 years: “Use 1 suppository every 4 to 6 hours (maximum of 5 doses in 24 hours)”. Under 3 years: “Do not use unless directed by a doctor”.

Can I give an acetaminophen suppository to a baby?

Only the 80 mg infants’ strength has directions for babies: 6 to 11 months, 1 suppository every 6 hours, maximum 4 doses in 24 hours. Under 6 months the label says “Do not use unless directed by a doctor”.

Can I cut a suppository in half?

None of the labels we read gives directions for cutting a suppository. If the strength on your box does not match your child’s age on its chart, the labels say to use it only as directed by a doctor.

Is a suppository dose the same as a liquid dose?

The suppository labels dose by age, while the AAP chart for liquid acetaminophen doses by weight, so the two charts do not line up row for row. Studies in hospital settings have found blood levels after suppositories vary, which is one reason not to mix routes without a doctor’s guidance.

Can I give a suppository and liquid acetaminophen together?

No. Every label says not to use it “with any other drug containing acetaminophen (prescription or nonprescription)”. Both count toward the same daily limit.

The Bottom Line

Acephen and other acetaminophen suppositories come in 80, 120, 325 and 650 mg, and each strength has its own age chart on the box. The 650 mg suppository is for ages 12 and up, at most six in 24 hours; the 120 mg is for ages 3 to 6, at most five doses; the 80 mg infants’ suppository covers 6 to 36 months; and below the youngest age on your box, the label’s direction is to use it only as a doctor says. Read the milligrams before the brand, never stack it with other acetaminophen, and if you are dosing by weight, use the liquid chart and your child’s doctor rather than the suppository box.

Sources

1. National Library of Medicine, RxNorm (RxNav). Acephen: acetaminophen 120 mg rectal suppository (RxCUI 209352), 325 mg (209360), 650 mg (209363). RxNav. Checked 13 October 2026.
2. DailyMed. Acephen (acetaminophen) suppository, Central Texas Community Health Centers, published 10 March 2016; 325 mg box label, G&W Labs; no directions text. Set ID aa6314c7-e816-4bb5-811c-5975fce1f743. dailymed.nlm.nih.gov. Checked 13 October 2026.
3. DailyMed. FeverAll Infants’ (acetaminophen 80 mg) suppository, Sun Pharmaceutical Industries. “under 6 months Do not use unless directed by a doctor”; “6 to 11 months Use 1 suppository every 6 hours (maximum of 4 doses in 24 hours)”; “12 to 36 months Use 1 suppository every 4 to 6 hours (maximum of 5 doses in 24 hours)”; liver warning; “this product does not contain directions or warnings for adult use”. Set ID 3ade895b-5dca-4d81-9415-8091923162ff. dailymed.nlm.nih.gov. Checked 13 October 2026.
4. DailyMed. FeverAll Children’s (acetaminophen 120 mg) suppository, Sun Pharmaceutical Industries. “under 3 years Do not use unless directed by a doctor”; “3 to 6 years Use 1 suppository every 4 to 6 hours (maximum of 5 doses in 24 hours)”. Set ID 861e2987-5473-45b0-b2a6-f980a9b0e809. dailymed.nlm.nih.gov. The same 120 mg directions appear on CVS (9d89544f-3a66-4f23-b609-381d027e0c95) and Walgreens (f2085b26-5778-4656-8de3-9edd83f914dd) labels. Checked 13 October 2026.
5. DailyMed. FeverAll Jr. Strength (acetaminophen 325 mg) suppository, Sun Pharmaceutical Industries. “under 6 years do not use”; “6 to 12 years Use 1 suppository every 4 to 6 hours. (maximum of 5 doses in 24 hours)”; “adults and children 12 years and older Use 2 suppositories every 4 to 6 hours. (maximum of 6 doses)”. Set ID 3561bbc3-53b0-4857-8b71-39e165ed95ce. dailymed.nlm.nih.gov. Checked 13 October 2026.
6. DailyMed. Acetaminophen 650 mg suppository, Padagis Israel Pharmaceuticals. “adults and children 12 years and older: 1 suppository every 4 to 6 hours while symptoms last”; “do not exceed 6 suppositories in any 24 hour period”; “children under 12 years: ask a doctor”; “Do not use in children under 12 years”; alcohol, liver disease and warfarin warnings; stop use if “fever lasts more than 3 days (72 hours), or recurs”; Poison Control 1-800-222-1222. Six suppositories of 650 mg is 3,900 mg (our arithmetic from the label count). Set ID b43974c3-4db9-4201-beee-b22596a2b241. dailymed.nlm.nih.gov. Same directions on Foster & Thrive 650 mg (23780dab-91d8-434f-9342-f5f1ba0a3c0a). Checked 13 October 2026.
7. DailyMed. Tylenol Extra Strength (acetaminophen 500 mg) caplets: “do not take more than 6 caplets in 24 hours, unless directed by a doctor” (6 caplets of 500 mg is 3,000 mg). Set ID 103d109d-f520-409c-8da2-eb6b0fbec891. dailymed.nlm.nih.gov. Checked 12 October 2026.
8. Birmingham PK, et al. Twenty-four-hour pharmacokinetics of rectal acetaminophen in children: an old drug with new recommendations. Anesthesiology, 1997;87(2):244-252. 28 children; “Most patients did not achieve peak or sustained serum values in the 10-20 microg/ml serum concentration range associated with antipyresis”; absorption “is a function of zero-order dissolution of suppositories and first-order absorption from the rectum”. PMID 9286887. Checked 13 October 2026.
9. Singla NK, et al. Plasma and cerebrospinal fluid pharmacokinetic parameters after single-dose administration of intravenous, oral, or rectal acetaminophen. Pain Practice, 2012. 6 healthy men; “Absorption phase, variability in plasma, and CSF were greater in PO and PR groups than variability with IV administration.” PMID 22524979. Checked 13 October 2026.
10. van der Marel CD, et al. Analgesic efficacy of rectal versus oral acetaminophen in children after major craniofacial surgery. Clinical Pharmacology & Therapeutics, 2001. 40 children; “9 of all 40 patients (22.5%) did not reach the expected analgesic acetaminophen plasma concentrations of 10- to 20 mg/L”. PMID 11452248. Checked 13 October 2026.

This page is general information copied from product labels, not medical advice for your child or for you. Follow the label on the package you have, which may be newer than the versions quoted here, and ask a doctor or pharmacist when the label tells you to.