Drug & supplement interaction

Delta-9-tetrahydrocannabinol (thc) + nitisinone

nitisinone brand names: Orfadin, Nityr.

Moderate Interaction
Medically reviewed by · Updated September 2026
The bottom line Moderate

Delta-9-tetrahydrocannabinol (thc) has a moderate interaction with nitisinone. Theoretically, drugs that are CYP2C9 inhibitors might increase the levels and adverse effects of THC.

Read the full interaction report
SeverityModerate
LikelihoodPossible
EvidenceD
What do Severity, Likelihood & Evidence mean?
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Interaction report

Delta-9-tetrahydrocannabinol (thc) and nitisinone

Here is the interaction we found between these two, with the evidence behind it.

Moderate

CYTOCHROME P450 2C9 (CYP2C9) INHIBITORS

Why this applies to nitisinone

nitisinone falls under CYTOCHROME P450 2C9 (CYP2C9) INHIBITORS — the group Delta-9-tetrahydrocannabinol (thc) interacts with.

Theoretically, drugs that are CYP2C9 inhibitors might increase the levels and adverse effects of THC.
THC is a substrate of CYP2C9 enzymes.
Severity Moderate Likelihood Possible Evidence D

Interaction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.

Dr. Brian Staiger, PharmD, BCPS
Dr. Brian Staiger explains PharmD, Clinical Pharmacist

Here's the key thing to understand about pairing nitisinone with THC: in this case, it's the nitisinone that may affect the THC, not the other way around. Nitisinone can block an enzyme called CYP2C9, which is one of the enzymes your liver uses to break down THC. If that breakdown slows, THC can build up a bit more than usual.

In plain terms, you might feel the THC more strongly, with effects like a stronger high, dizziness, sleepiness, a faster heartbeat, or feeling foggy. I'll be honest, this is a theoretical concern based on how these compounds behave, not something well documented in real patients. Still, it's worth a quick chat with your pharmacist or doctor before combining them, and never adjust your nitisinone on your own.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Product information for Marinol. AbbVie. North Chicago, IL 60064. August 2017. Available at: https://www.accessdata.fda.gov/drugsatfda_docs/label/2017/018651s029lbl.pdf.

What These Ratings Mean

Every interaction above is graded three ways — here’s the key to each label.

Severity how clinically significant the interaction is
Major

Clinically significant. Avoid the combination, or use only under close professional supervision.

Moderate

Usually worth avoiding or managing — may need monitoring, a dose change, or timing apart.

Minor

Generally not serious. Be aware of it and mention it to your pharmacist.

Likelihood how strong the evidence is that the interaction actually happens in people
  • LikelyWell-controlled human studies have demonstrated the likely existence of this interaction.
  • ProbableInteraction has not been documented in well-controlled studies, however, the interaction has been demonstrated in some small human studies or in controlled animal studies in conjunction with multiple case reports.
  • PossibleInteraction has been documented in animal or in lab research, or the interaction has been documented in humans but is limited to case reports or conflicting clinical research exists.
  • UnlikelyInteraction has been demonstrated in animal or in lab research but has been shown not to occur in humans.
Evidence the quality of the studies behind the rating (graded A–D)
  • AHigh-quality meta-analysis (quantitative systematic review).
  • BCase-control study.
  • CConsensus.
  • DAnecdotal evidence.

These ratings are for information only. Never start, stop, or otherwise change your therapy before speaking with your provider.

Keep it in perspective

Delta-9-tetrahydrocannabinol (thc) Also Interacts With Other Medications

Delta-9-tetrahydrocannabinol (thc) has 761 moderate, 336 minor known drug interactions in our database — the nitisinone one above is one of them. If you take anything else, check it against the full list below.

Moderate 761 Minor 336 No known interaction 1,733 (incl. nitisinone)
Taking anything else?

Check Another of Your Medications Against Delta-9-tetrahydrocannabinol (thc)

Covers the 2,830 medications we’ve checked against Delta-9-tetrahydrocannabinol (thc). Pick one to open its full report.

Everything else you take

See Every Supplement That Interacts With nitisinone

This page covers Delta-9-tetrahydrocannabinol (thc) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the nitisinone page lists 21 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Cannabinol (cbn) (moderate), Cannabis (moderate), Coffee Charcoal (moderate) and European Mandrake (moderate).

By severity: 1 major · 11 moderate · 9 minor.

From our pharmacist’s overview on the nitisinone page

“For a child or adult with hereditary tyrosinemia type 1, nitisinone (Orfadin, Nityr) is the medication holding a dangerous metabolic disease in check, which is why the 21 supplements on this page warrant genuine care rather than a shrug. Activated charcoal is the single major-rated entry and the one to understand first, since it can so…”

Reviewed by 2 · Jul 18, 2026

Open the nitisinone interaction page

How much people look this up

Where Delta-9-tetrahydrocannabinol (thc) and nitisinone Sit Against Everything Else

Out of every supplement and medication people look up on HelloPharmacist, here is where these two land this week — and which way each has been moving.

Supplement Delta-9-tetrahydrocannabinol (thc)
Top half

#518 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication nitisinone
Top half

#868 of 2,830 medications looked up here in the last 7 days

29 days ago today

Position among everything looked up on this site, not a measure of how commonly either one is used or how important it is. A supplement can climb this list because of a news story. It counts every request to the page, automated ones included, and nothing here identifies anyone.

Supplement

About Delta-9-tetrahydrocannabinol (thc)

What is Delta-9-tetrahydrocannabinol (thc)?

Delta-9-tetrahydrocannabinol (thc)
  • Chronic or nerve pain
  • Nausea and vomiting from chemotherapy
  • Appetite loss and weight loss
  • Muscle spasticity
  • Sleep problems
  • Anxiety and stress

THC is the main mind-altering compound in cannabis and is best known for causing a 'high.' A prescription form (dronabinol) is approved for chemotherapy-related nausea and appetite loss, but for most other uses the evidence is mixed or limited, and THC can impair thinking and driving. It should be avoided in pregnancy and breastfeeding and used only with medical guidance.

Read the full Delta-9-tetrahydrocannabinol (thc) monograph & all interactions
Medication

About Nitisinone

What Is Nitisinone Used For?

Brand names: Orfadin, Nityr

Nitisinone (as Orfadin capsules, Orfadin oral suspension, Nityr tablets, and generic Nitisinone capsules) is used to treat hereditary tyrosinemia type 1 (HT-1) — a rare inherited disease in which the body cannot properly break down the amino acid tyrosine, leading to toxic buildup that damages the liver and kidneys. It is used in both adults and children, always together with a strict low-tyrosine, low-phenylalanine diet.

Harliku tablets are approved for a different rare inherited condition: alkaptonuria (AKU). In adults with AKU, Harliku reduces the level of homogentisic acid (HGA) — a harmful substance that builds up in the urine and body tissues. Harliku is not approved for HT-1, and the other nitisinone products are not approved for AKU.

See full Nitisinone drug information
Keep checking

Other Drugs & Delta-9-tetrahydrocannabinol (thc)

Browse every other medication we’ve checked against Delta-9-tetrahydrocannabinol (thc) — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
761Moderate
336Minor
1,732No known interaction
761 Moderate 336 Minor 1,732 No interaction
Moderate

761 interactions

Showing 60 of 761 moderate interactions — see all 761 on the Delta-9-tetrahydrocannabinol (thc) page.

Minor

336 interactions

Showing 60 of 336 minor interactions — see all 336 on the Delta-9-tetrahydrocannabinol (thc) page.

No interaction 1,732 drugs checked — show the list

We also checked Delta-9-tetrahydrocannabinol (thc) against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,732 medications checked with no known interaction — see the full Delta-9-tetrahydrocannabinol (thc) list.

See the full Delta-9-tetrahydrocannabinol (thc) interactions page
See every supplement checked against nitisinone, ranked by severity
Sources

Sources & How We Checked

Interaction details are evidence-graded and sourced from the Natural Medicines database. The medication overview comes from MedlinePlus.

Content is written and reviewed by licensed HelloPharmacist pharmacists. See our data sources and editorial standards for how this information is built and checked.

Parts of this content are provided by the Therapeutic Research Center, LLC.

DISCLAIMER: Currently this does not check for drug-drug interactions. This is not an all-inclusive comprehensive list of potential interactions and is for informational purposes only. Not all interactions are known or well-reported in the scientific literature, and new interactions are continually being reported. Input is needed from a qualified healthcare provider including a pharmacist before starting any therapy. Application of clinical judgment is necessary.

© 2021 Therapeutic Research Center, LLC

Keep exploring
Delta-9-tetrahydrocannabinol (thc) monograph › Uses, safety, and every drug interaction in one place nitisinone supplement interactions › Every supplement checked against nitisinone, ranked by severity Nitisinone drug information › The full plain-English guide to this medication Supplement interaction checker › Check any supplement or product against your medications Browse medications A–Z › Every drug we've checked against herbs & supplements Ask a pharmacist › Free, personal answer from our licensed team
Pharmacist Counseling Corner

Taking Delta-9-tetrahydrocannabinol (thc) and nitisinone Together: Common Questions

Can you take Delta-9-tetrahydrocannabinol (thc) with nitisinone?
There is a moderate interaction, so it may be acceptable with monitoring or timing changes — but check with your pharmacist first. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Delta-9-tetrahydrocannabinol (thc) and nitisinone interaction?
We rate it Moderate. This combination may require monitoring, a dose adjustment, or separating the times you take each one. Consult your pharmacist before using them together.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

Still Have a Question About nitisinone and Delta-9-tetrahydrocannabinol (thc)?

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This information is for education only and is not a substitute for professional medical advice. Always check with your pharmacist or doctor before starting, stopping, or combining supplements and medications.