Drug & supplement interaction

Delta-9-tetrahydrocannabinol (thc) + Ivermectin

Ivermectin brand names: Stromectol, Mectizan, Sklice, Soolantra.

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

Delta-9-tetrahydrocannabinol (thc) has a moderate interaction with Ivermectin. Theoretically, THC might alter levels of drugs that are substrates of P-glycoprotein (P-gp).

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 Ivermectin

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

Moderate

P-GLYCOPROTEIN SUBSTRATES

Why this applies to Ivermectin

Ivermectin falls under P-GLYCOPROTEIN SUBSTRATES — the group Delta-9-tetrahydrocannabinol (thc) interacts with.

Theoretically, THC might alter levels of drugs that are substrates of P-glycoprotein (P-gp).
Most in vitro research suggests that THC can inhibit P-gp and increase the accumulation of probe compounds by reducing P-gp mediated drug efflux. In vitro studies in kidney cell lines show that a 1-hour exposure to CBD and THC inhibits P-gp. THC may also alter the expression of P-gp, although this effect appears to vary based on duration of exposure. Some in vitro research in lymphoblastoid leukemia cell lines indicates that a 1-hour exposure to cannabinoids does not affect P-gp expression, while a prolonged 72-hour exposure decreases P-gp expression. Other in vitro research in these cell lines shows that a 4-hour exposure to THC and CBD induces P-gp gene expression, while exposure for longer than 4 hours and up to 48 hours does not induce P-gp gene expression.
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 basic idea with ivermectin and THC. Your body uses a kind of cellular bouncer called P-glycoprotein (P-gp) to push ivermectin back out of cells and limit how much reaches your brain. Lab studies suggest THC may slow that pump down. If the pump works less, a bit more ivermectin could hang around, which in theory could mean more side effects like dizziness, drowsiness, nausea, or low blood pressure.

I want to be honest, though: this is theoretical, coming from cell and animal studies only, not from people. For a typical one-time worming dose, it's unlikely to cause trouble for most folks. Still, since both can make you sleepy, check with your pharmacist or doctor before combining them.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Zhu, H. J., Wang, J. S., Markowitz, J. S., Donovan, J. L., Gibson, B. B., Gefroh, H. A., and Devane, C. L. Characterization of P-glycoprotein inhibition by major cannabinoids from marijuana. J Pharmacol Exp.Ther. 2006;317(2):850-857. PubMed
  2. Holland, M. L., Panetta, J. A., Hoskins, J. M., Bebawy, M., Roufogalis, B. D., Allen, J. D., and Arnold, J. C. The effects of cannabinoids on P-glycoprotein transport and expression in multidrug resistant cells. Biochem.Pharmacol 4-14-2006;71(8):1146-115 PubMed
  3. Tournier N, Lucie Chevillard L, Megarbane B, et al. Interaction of drugs of abuse and maintenance treatments with human P-glycoprotein (ABCB1) and breast cancer resistance protein (ABCG2). Int J Neuropsychopharmacol. 2010;13(7):905-15. PubMed
  4. Arnold JC, Hone P, Holland ML, Allen JD. CB2 and TRPV1 receptors mediate cannabinoid actions on MDR1 expression in multidrug resistant cells. Pharmacol Rep. 2012;64(3):751-7. PubMed

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 Ivermectin 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. Ivermectin)
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.

From our Q&A

Questions About Delta-9-tetrahydrocannabinol (thc) or Ivermectin

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Delta-9-tetrahydrocannabinol (thc) or Ivermectin, not necessarily both, but if one is close to what you were about to ask it will usually go further than a database entry can:

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

Everything else you take

See Every Supplement That Interacts With Ivermectin

This page covers Delta-9-tetrahydrocannabinol (thc) only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Ivermectin page lists 58 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), St. John's Wort (major), Sweet Orange (major), Bitter Melon (moderate) and Black Pepper (moderate).

By severity: 3 major · 37 moderate · 18 minor.

Open the Ivermectin interaction page

How much people look this up

Where Delta-9-tetrahydrocannabinol (thc) and Ivermectin 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

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

29 days ago today
Medication Ivermectin
Top 1%

#12 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 Ivermectin

What Is Ivermectin Used For?

Brand names: Stromectol, Mectizan, Sklice, Soolantra

Ivermectin tablets (including Stromectol) are used to treat two parasitic infections: strongyloidiasis (a roundworm infection of the intestinal tract) and onchocerciasis (river blindness, caused by a parasitic worm spread by blackfly bites). These are prescription uses for serious infections.

Topical ivermectin lotion — sold under several names including RID One and Done, Head Lice Treatment Ivermectin Lotion, Scalp Care Lotions, and others — is applied to the scalp to treat head lice. A separate topical ivermectin cream (1%), available as Soolantra and ivermectin cream 1%, is used to treat the inflammatory pimple-like bumps of rosacea.

See full Ivermectin 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 Ivermectin, 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 Ivermectin supplement interactions › Every supplement checked against Ivermectin, ranked by severity Ivermectin 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 Ivermectin Together: Common Questions

Can you take Delta-9-tetrahydrocannabinol (thc) with Ivermectin?
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 Ivermectin 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 Ivermectin 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.