Drug & supplement interaction

Sweet Clover + Interferon Alfa-2b

Interferon Alfa-2b brand names: Rebetron, Intron A, Viraferon.

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

Sweet Clover has a moderate interaction with Interferon Alfa-2b. Theoretically, concomitant use of sweet clover with hepatoxic drugs might increase the risk of hepatotoxicity.

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

Sweet Clover and Interferon Alfa-2b

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

Moderate

HEPATOTOXIC DRUGS

Why this applies to Interferon Alfa-2b

Interferon Alfa-2b falls under HEPATOTOXIC DRUGS — the group Sweet Clover interacts with.

Theoretically, concomitant use of sweet clover with hepatoxic drugs might increase the risk of hepatotoxicity.
Orally, large amounts of sweet clover can cause transient liver injury in susceptible individuals, possibly due to coumarin content. In one case report, a patient with multiple sclerosis developed jaundiced palms and a slight elevation in serum alanine aminotransferase (ALT) after taking sweet clover containing coumarin 10 mg daily for 3 years. Two weeks after starting therapy with subcutaneous interferon (IFN)-beta 1b, aspartate transaminase (AST) and ALT levels increased to 7 and 17 times the upper limit of normal, respectively. Levels normalized after discontinuation of both products. Subsequent use of IFN-beta 1a alone, without sweet clover, resulted in only a very slight increase in AST.
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 concern with pairing sweet clover and Interferon Alfa-2b. This isn't about one speeding up or slowing down the other. Instead, both can be tough on the liver. Interferon Alfa-2b is already known to raise liver enzymes (your AST and ALT), and sweet clover's coumarin content can stress the liver too, especially in larger supplement doses or if the plant has spoiled. Stacking two liver stressors may add up.

Honestly, this is a theoretical worry built mostly on how these things work, plus one case report with a related interferon. It hasn't been firmly proven. Still, since your team likely checks your liver labs during interferon treatment, it's worth telling your doctor or pharmacist before adding sweet clover.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  2. Tamura S, Warabi Y, Matsubara S. Severe liver dysfunction possibly caused by the combination of interferon beta-1b therapy and melilot (sweet clover) supplement. J Clin Pharm Ther 2012;37(6):724-5. 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

Sweet Clover Also Interacts With Other Medications

Sweet Clover has 479 moderate known drug interactions in our database — the Interferon Alfa-2b one above is one of them. If you take anything else, check it against the full list below.

Moderate 479 No known interaction 2,351 (incl. Interferon Alfa-2b)
Taking anything else?

Check Another of Your Medications Against Sweet Clover

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

Everything else you take

See Every Supplement That Interacts With Interferon Alfa-2b

This page covers Sweet Clover only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Interferon Alfa-2b page lists 57 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Beer (major), Siberian Cocklebur (major), Wine (major), Alfalfa (moderate) and Angelica Archangelica (moderate).

By severity: 3 major · 53 moderate · 1 minor.

From our pharmacist’s overview on the Interferon Alfa-2b page

“People taking interferon alfa-2b (Intron A, Rebetron) are usually treating hepatitis or a cancer, so the liver may already be under strain, and that is exactly where most of this list points. Of the 57 supplements on file, 38 can add to liver stress, and all three major-rated interactions sit in that group: Siberian cocklebur, which ha…”

Reviewed by 2 · Jul 18, 2026

Open the Interferon Alfa-2b interaction page

One more smart check

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

We hold 26 real supplement products containing Sweet Clover, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Sweet Clover. Your product may carry other ingredients that interact with Interferon Alfa-2b too, on top of Sweet Clover — 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 Sweet Clover and Interferon Alfa-2b 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 Sweet Clover
Steady interest

#1,375 of 1,452 supplements looked up here in the last 7 days

29 days ago today
Medication Interferon Alfa-2b
Top half

#1,234 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 Sweet Clover

What is Sweet Clover?

Sweet Clover
  • Varicose veins and poor circulation
  • Leg swelling (edema)
  • Hemorrhoids
  • Bruising and minor inflammation
  • Respiratory complaints

Sweet clover is a traditional European herb most often promoted for vein problems and leg swelling, but high-quality human evidence is limited. It contains coumarin, which can become dangerous if the plant spoils, so quality matters and you should talk to a pharmacist before using it.

Read the full Sweet Clover monograph & all interactions
Medication

About Interferon Alfa-2b Injection

What Is Interferon Alfa-2b Injection Used For?

Brand names: Rebetron, Intron A, Viraferon

  • Interferon alfa-2b injection is used to treat a number of conditions.

  • Interferon alfa-2b injection is used

    • alone or in combination with ribavirin (Copegus, Rebetol, Ribasphere) to treat chronic (long-term) hepatitis C infection (swelling of the liver caused by a virus) in people who show signs of liver damage,

    • to treat chronic hepatitis B infection (swelling of the liver caused by a virus) in people who show signs of liver damage,

    • to treat hairy cell leukemia (a white blood cell cancer),

    • to treat genital warts,

    • to treat Kaposi's sarcoma (a type of cancer that causes abnormal tissue to grow on different parts of the body) related to acquired immunodeficiency syndrome (AIDS),

    • to treat malignant melanoma (a cancer that begins in certain skin cells) in certain people who have had surgery to remove the cancer,

    • along with another medication to treat follicular non-Hodgkin's lymphoma (NHL; a slow-growing blood cancer).

  • Interferon alfa-2b is in a class of medications called immunomodulators. Interferon alfa-2b works to treat hepatitis C virus (HCV) and hepatitis B virus (HBV) by decreasing the amount virus in the body. Interferon alfa-2b may not cure hepatitis B or hepatitis C or prevent you from developing complications from these infections such as cirrhosis (scarring) of the liver, liver failure, or liver cancer. It also may not prevent the spread of hepatitis B or C to other people. It is not known exactly how interferon alfa-2b works to treat cancer or genital warts.

See full Interferon Alfa-2b Injection drug information
Keep checking

Other Drugs & Sweet Clover

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

0Major
479Moderate
0Minor
2,350No known interaction
479 Moderate 2,350 No interaction
Moderate

479 interactions

Showing 60 of 479 moderate interactions — see all 479 on the Sweet Clover page.

No interaction 2,350 drugs checked — show the list

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

Showing the 60 most looked-up of 2,350 medications checked with no known interaction — see the full Sweet Clover list.

See the full Sweet Clover interactions page
See every supplement checked against Interferon Alfa-2b, 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
Sweet Clover monograph › Uses, safety, and every drug interaction in one place Interferon Alfa-2b supplement interactions › Every supplement checked against Interferon Alfa-2b, ranked by severity Interferon Alfa-2b Injection 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 Sweet Clover and Interferon Alfa-2b Together: Common Questions

Can you take Sweet Clover with Interferon Alfa-2b?
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 Sweet Clover and Interferon Alfa-2b 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 Interferon Alfa-2b and Sweet Clover?

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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.