Drug & supplement interaction

Licorice + Morphine Sulfate

Morphine Sulfate brand names: MS Contin, Kadian, Avinza, Morphabond, Arymo ER.

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

Licorice has a moderate interaction with Morphine Sulfate. Theoretically, licorice might decrease the absorption of P-glycoprotein substrates.

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

Licorice and Morphine Sulfate

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

Moderate

P-GLYCOPROTEIN SUBSTRATES

Why this applies to Morphine Sulfate

Morphine Sulfate falls under P-GLYCOPROTEIN SUBSTRATES — the group Licorice interacts with.

Theoretically, licorice might decrease the absorption of P-glycoprotein substrates.
In vitro research shows that licorice can increase P-glycoprotein activity.
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 idea behind this pairing. Your body uses a tiny pump called P-glycoprotein to move certain drugs around and limit how much gets absorbed. Lab studies suggest licorice may rev up that pump, which could push a bit more morphine back out and possibly leave you with slightly less in your system. In plain terms, your morphine might not control pain quite as well.

I want to be honest about how soft this evidence is. It comes only from test-tube and animal research, not from people, so we really don't know if it matters in real life. For most folks, a little licorice flavoring in candy or tea is unlikely to change anything. Still, since morphine is for serious pain, mention any regular licorice supplement use to your pharmacist or doctor before changing a thing.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Wang H, Dong L, Qu F, et al. Effects of glycyrrhizin on the pharmacokinetics of nobiletin in rats and its potential mechanism. Pharm Biol. 2020 Dec;58(1):352-356. 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

Licorice Also Interacts With Other Medications

Licorice has 977 moderate, 63 minor known drug interactions in our database — the Morphine Sulfate one above is one of them. If you take anything else, check it against the full list below.

Moderate 977 Minor 63 No known interaction 1,790 (incl. Morphine Sulfate)
Taking anything else?

Check Another of Your Medications Against Licorice

Covers the 2,830 medications we’ve checked against Licorice. Pick one to open its full report.

From our Q&A

Questions About Licorice or Morphine Sulfate

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Licorice or Morphine Sulfate, 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 Morphine Sulfate

This page covers Licorice only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Morphine Sulfate page lists 172 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: 1,4-butanediol (major), Activated Charcoal (major), Beer (major), Gamma-hydroxybutyrate (ghb) (major) and Kava (major).

By severity: 8 major · 138 moderate · 26 minor.

From our pharmacist’s overview on the Morphine Sulfate page

“With morphine sulfate (MS Contin, Kadian, Avinza), an opioid powerful enough to slow breathing on its own, this list warrants genuine respect. Of the 172 supplements and foods on file, 8 carry a major rating, and most of those pile extra sedation onto a drug that already sedates.”

Reviewed by 2 · Jul 18, 2026

Open the Morphine Sulfate interaction page

One more smart check

Taking Licorice as Part of a Dietary Supplement Product? Check It for Interactions

We hold 4,721 real supplement products containing Licorice, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Licorice. Your product may carry other ingredients that interact with Morphine Sulfate too, on top of Licorice — and those would not show on this page. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Licorice and Morphine Sulfate 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 Licorice
Top 5%

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

29 days ago today
Medication Morphine Sulfate
Top half

#1,001 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 Licorice

What is Licorice?

Licorice
  • Sore throat and cough
  • Heartburn and stomach upset
  • Mouth ulcers and digestive complaints
  • Inflammation
  • Traditional tonic/adrenal support

Licorice root is a traditional remedy used for sore throats, coughs, and digestive complaints, but solid human evidence is limited for most uses. Regular licorice contains glycyrrhizin, which can raise blood pressure and lower potassium when taken in large amounts or for a long time, so deglycyrrhizinated (DGL) products are often preferred. Talk to your pharmacist or doctor before using it, especially if you have high blood pressure, heart, or kidney problems.

Read the full Licorice monograph & all interactions
Medication

About Morphine

What Is Morphine Used For?

Brand names: MS Contin, Kadian, Avinza, Morphabond, Arymo ER

Morphine is used for pain that is severe enough to need an opioid and that other treatments cannot control well. It is meant for people who have not done well on, or cannot tolerate, other options.

Some uses depend on the product. Morphine sulfate tablets treat acute pain in adults and in children weighing at least 50 kg, and chronic pain in adults. Morphine oral solution (2 mg/mL and 4 mg/mL) treats acute and chronic pain in adults and acute pain in children 2 years and older. The 20 mg/mL oral solution is only for opioid-tolerant adults. Extended-release capsules and tablets, including MS Contin, are for severe, persistent pain that needs daily, long-term opioid treatment. Duramorph and preservative-free morphine injection can be given by vein, or into the epidural or intrathecal space (around the spinal cord). Infumorph and Mitigo are only for continuous epidural or intrathecal infusion for intractable chronic pain.

See full Morphine drug information
Keep checking

Other Drugs & Licorice

Browse every other medication we’ve checked against Licorice — both the ones with a known interaction and the ones without. Select any drug for the full detail.

0Major
977Moderate
63Minor
1,789No known interaction
977 Moderate 63 Minor 1,789 No interaction
Moderate

977 interactions

Showing 60 of 977 moderate interactions — see all 977 on the Licorice page.

Minor

63 interactions

Showing 60 of 63 minor interactions — see all 63 on the Licorice page.

No interaction 1,789 drugs checked — show the list

We also checked Licorice against these medications and found no known interaction in our sources. Open any page to confirm.

Showing the 60 most looked-up of 1,789 medications checked with no known interaction — see the full Licorice list.

See the full Licorice interactions page
See every supplement checked against Morphine Sulfate, 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
Licorice monograph › Uses, safety, and every drug interaction in one place Morphine Sulfate supplement interactions › Every supplement checked against Morphine Sulfate, ranked by severity Morphine 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 Licorice and Morphine Sulfate Together: Common Questions

Can you take Licorice with Morphine Sulfate?
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 Licorice and Morphine Sulfate 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 Morphine Sulfate and Licorice?

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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.