Acetaminophen Rectal and Flucloxacillin: Interaction Details
AI-assisted, pharmacist-reviewed · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature
Flucloxacillin
No brand names on recordAcetaminophen Rectal
How we grade severity & evidence
Severity levels
- Contraindicated: These should generally not be used together.
- Major: Potentially serious — often needs a change or close monitoring.
- Moderate: Can be significant — usually manageable with monitoring.
- Minor: Usually limited clinical impact.
Evidence grades
- Established: Well documented — supported by controlled studies or strong clinical data.
- Probable: Good supporting evidence, though not definitively proven.
- Suspected: Some evidence suggests this interaction, but it is not well established.
- Possible: Limited or conflicting evidence; the interaction may occur.
- Theoretical: Predicted from the drugs' pharmacology; not yet confirmed in people.
Ratings come from the documented interaction literature and are reviewed by a pharmacist. They describe the documented risk of the combination, not what will necessarily happen to you — your dose, timing, and health picture all matter.
What happens
An increased risk of high anion gap metabolic acidosis (HAGMA)
Interaction Deep Dive
Exert caution when flucloxacillin is coadministered with acetaminophen due to the increased risk high anion gap metabolic acidosis (HAGMA). After coadministration of flucloxacillin and acetaminophen, a close monitoring is recommended in order to detect the appearance of acid-base disorders, namely HAGMA, including the search of urinary 5-oxoproline. If flucloxacillin is continued after cessation of paracetamol, it is advisable to ensure that there are no signals of HAGMA, as there is a possibility of flucloxacillin maintaining the clinical picture of HAGMA1.
Why it happens (mechanism)
Unknown
Common questions
Can I take Acetaminophen Rectal and Flucloxacillin together?
An increased risk of high anion gap metabolic acidosis (HAGMA) Always confirm with your pharmacist or prescriber before making any change.
How serious is the Acetaminophen Rectal and Flucloxacillin interaction?
It is rated major. Potentially serious — often needs a change or close monitoring.
How quickly could this interaction happen?
The documented onset is "unspecified". The timing of this interaction is not well characterized.
How strong is the evidence for this interaction?
The evidence is graded "theoretical". Predicted from the drugs' pharmacology; not yet confirmed in people.
Questions for your pharmacist
- Does my dose of Acetaminophen Rectal or Flucloxacillin need adjusting while I take them together?
- What symptoms should prompt me to call you or my prescriber right away?
- Does the timing of my doses matter for this combination?
- Is there a safer alternative to one of these medications for me?
References (1)
- Product Information: FLUCILLIN oral capsules, flucloxacillin oral capsules. Pinewood Laboratories Ltd, Ballymacarbry, Tipperary, Ireland, 2023.
Keep reading about Flucloxacillin
Keep reading about Acetaminophen Rectal
These medications also interact with supplements
Prescription drugs aren't the whole picture — herbal and dietary supplements can interact with them too. From the evidence-graded Natural Medicines database:
major · moderate · minor — check everything you take with our drug–supplement interaction checker.
Check another combination
Our instant two-drug interaction checker is almost here.
Still have questions about this combination?
Every question gets a real answer from a licensed pharmacist — free, and usually within a day.
Ask the pharmacist