Drug Interaction Report

Nitisinone and Acyclovir: Interaction Details

A pharmacist-reviewed analysis of the Nitisinone and Acyclovir interaction: the documented clinical effects, severity rating, onset, mechanism, and management considerations, with cited references throughout.

AI-assisted, pharmacist-reviewed · Source data updated Jul 10, 2026 · Sources: FDA labeling, DDInter 2.0, cited literature

Acyclovir

Avaclyr Sitavig Sitavig® Zovirax Zovirax® Capsules Zovirax® Tablets
+

Nitisinone

No brand names on record
Dr. Brian Staiger, PharmD, BCPS
Medically reviewed by
Dr. Brian Staiger, PharmD, BCPS
Updated Jul 10, 2026
Editorial policy · Data sources
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Interaction severity
Major
Potentially serious — often needs a change or close monitoring.
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.

Of 22 documented Nitisinone interactions, 21 are rated major — including this one.
Worried about symptoms right now? Contact your pharmacist or prescriber, or call Poison Control at 1-800-222-1222 (US). Call 911 for an emergency.
Onset
unspecified
Evidence
probable
Severity
Major

What happens

Increased OAT1 or OAT3 substrate exposure and an increased risk of OAT1 or OAT3 substrate-related adverse effects

Interaction Deep Dive

Concomitant use of nitisinone, an inhibitor of OAT1 and OAT3, with OAT1 or OAT3 substrates may increase substrate exposure and potential adverse effects. Monitor for potential adverse reactions related to the substrate when using concomitantly with nitisinone. When nitisinone 80 mg once daily was coadministered with a 20 mg IV dose of furosemide (an OAT1/OAT3 substrate), furosemide AUC increased by 72% and Cmax increased by 12%12.

Why it happens (mechanism)

Inhibition of OAT1-mediated metabolism by nitisinone; inhibition of OAT3-mediated metabolism by nitisinone

Literature reports

1 report — tap to read

a) When nitisinone 80 mg once daily was coadministered with a 20 mg IV dose of furosemide (an OAT1/OAT3 substrate), furosemide AUC increased by 72% and Cmax increased by 12% 12.

Common questions

Can I take Nitisinone and Acyclovir together?

Increased OAT1 or OAT3 substrate exposure and an increased risk of OAT1 or OAT3 substrate-related adverse effects Always confirm with your pharmacist or prescriber before making any change.

How serious is the Nitisinone and Acyclovir 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 "probable". Good supporting evidence, though not definitively proven.

Questions for your pharmacist

  • Does my dose of Nitisinone or Acyclovir 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 (2)

  1. Product Information: NITYR(R) oral tablets, nitisinone oral tablets. Cycle Pharmaceuticals Ltd (per FDA), Lexington, KY, 2020. DailyMed
  2. Product Information: HARLIKU(TM) oral tablets, nitisinone oral tablets. Cycle Pharmaceuticals Ltd (per FDA), Boston, MA, 2025. DailyMed
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Acyclovir

Keep reading about Acyclovir

All Acyclovir interactions (25) Acyclovir drug information
Also serious with: Fezolinetant Bupropion Clomipramine Dichlorphenamide
Nitisinone

Keep reading about Nitisinone

All Nitisinone interactions (22)
Also serious with: Deuruxolitinib Acyclovir Injection Meropenem Injection Oseltamivir
Beyond drug–drug

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:

Acyclovir + Activated Charcoal Asarabacca Siberian Cocklebur African Wild Potato Aristolochia Banderol Biofeedback Caffeic Acid + 29 more
Nitisinone + Activated Charcoal Cannabinol (cbn) Cannabis Coffee Charcoal Delta-9-tetrahydrocannabinol (thc) European Mandrake Glucomannan Guar Gum + 13 more

major · moderate · minor — check everything you take with our drug–supplement interaction checker.

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This information is for education, not a substitute for professional medical advice. Do not start, stop, or change any medication without talking to your pharmacist or prescriber.