Drug & supplement interaction

Beta-sitosterol + Interferon Beta-1a

Interferon Beta-1a brand names: Rebif, Avonex.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 20, 2026
The bottom line No known interaction

We found no known interaction between Beta-sitosterol and Interferon Beta-1a in our sources. Absence of a documented interaction is not the same as proven safety, and does not guarantee one does not exist. Do not start, stop, or change a medication or supplement based on this page; confirm with your pharmacist or doctor first.

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Interaction report

Beta-sitosterol and Interferon Beta-1a

We checked these two against our interaction database. Here is what we found.

No Known Interaction Found

We did not find a documented interaction between Interferon Beta-1a and Beta-sitosterol in our sources. This does not guarantee that the combination is completely free of risk — there is often limited research on supplements and herbal products, especially around drug interactions.

Worth understanding: our licensed dataset holds no drug-interaction record for Beta-sitosterol at all — not against Interferon Beta-1a, and not against any other medication we track. This verdict therefore rests on the absence of any recorded data, not on research that looked at this combination and found nothing. We cannot rule an interaction out.

If you decide to take both, the practical routine is simple: add one new thing at a time and note the date you started it. If the combination is going to disagree with you, it usually shows in the first days to a couple of weeks — and a start date turns “I’ve been feeling off” into something a pharmacist can actually work with. Do not stop a prescribed medicine on your own.

Always talk with your pharmacist or doctor before making changes to your medications or supplements, particularly if you take several medications or have an ongoing health condition.

Beta-sitosterol safety at a glance

Beta-sitosterol overall Use caution Generally well tolerated for most adults when used short-term, but check with a healthcare provider first.
Pregnancy Avoid There is not enough safety data, so it is best to avoid supplemental use during pregnancy.
Breastfeeding Avoid There is not enough safety data, so it is best to avoid supplemental use while breastfeeding.

Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Interferon Beta-1a and Beta-sitosterol? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

What Beta-sitosterol Itself Has Been Linked To

This is not an interaction — nothing below involves Interferon Beta-1a. It is the side-effect record for Beta-sitosterol on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Beta-sitosterol, this list is the first place to look. One entry is worth acting on rather than waiting out — marked below.

  • Pancreatitis Worth acting on Additional detail

    “Orally, beta-sitosterol can cause nausea, indigestion, gas, diarrhea, or constipation. Beta-sitosterol can also reduce the appetite. There is a case report of acute pancreatitis thought to be associated with taking beta-sitosterol in a 57-year-old male.”

    Beta-sitosterol · Natural Medicines adverse-effect record, reported in constipation.

    5 sources cited
    1. 5327. Berges RR, Windeler J, Trampisch HJ, et al. Randomised, placebo-controlled, double-blind clinical trial of beta-sitosterol in patients with benign prostatic hyperplasia. Beta-sitosterol Study Group. Lancet 1995;345:1529-32.
    2. 5328. Klippel KF, Hiltl DM, Schipp B. A multicentric, placebo-controlled, double-blind clinical trial of beta-sitosterol (phytosterol) for the treatment of benign prostatic hyperplasia. Br J Urol 1997;80:427-32.
    3. 5334. Becker M, Staab D, Von Bergman K. Long-term treatment of severe familial hypercholesterolemia in children: effect of sitosterol and bezafibrate. Pediatrics 1992;89:138-42. DOI
    4. 106080. Lorenze A, Hsueh W, Nasr J. Beta-sitosterol-induced acute pancreatitis: A case report and review of the literature. Cureus. 2020;12(3):e7407. PubMed
    5. 15550. Prager N, Bickett K, French N, Marcovici G. A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia. J Altern Complement Med 2002
  • A change in sex drive / Erection problems Additional detail

    “Orally, beta-sitosterol can cause erectile dysfunction and loss of libido.”

    Beta-sitosterol · Natural Medicines adverse-effect record, reported in erectile dysfunction (ed).

    2 sources cited
    1. 5327. Berges RR, Windeler J, Trampisch HJ, et al. Randomised, placebo-controlled, double-blind clinical trial of beta-sitosterol in patients with benign prostatic hyperplasia. Beta-sitosterol Study Group. Lancet 1995;345:1529-32.
    2. 5329. Wilt TJ, MacDonald R, Ishani A. beta-sitosterol for the treatment of benign prostatic hyperplasia: a systematic review. BJU Int 1999;83:976-83. PubMed
  • Acne Additional detail

    “Orally, beta-sitosterol can worsen acne when taken alone or in combination with saw palmetto.”

    Beta-sitosterol · Natural Medicines adverse-effect record, reported in acne.

    2 sources cited
    1. 5331. Oster P, Schlierf G, Heuck CC, et al. [Sitosterol in familial hyperlipoproteinemia type II. A randomized, double-blind, cross-over study]. Dtsch Med Wochenschr 1976;101:1308-11.
    2. 15550. Prager N, Bickett K, French N, Marcovici G. A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia. J Altern Complement Med 2002
  • Bloating or gas / Reduced appetite Additional detail

    Recorded for Beta-sitosterol in the same Natural Medicines adverse-effect record shown under Pancreatitis above.

  • Stomach upset / Constipation / Diarrhea / Nausea Additional detail

    “Orally, beta-sitosterol is generally well tolerated. Topically, beta-sitosterol seems to be well tolerated.

    Most Common Adverse Effects:

    Orally: Constipation, diarrhea, gas, indigestion, and nausea.”

    Beta-sitosterol · Natural Medicines adverse-effect record, reported in constipation.

Everything above comes from the Natural Medicines adverse-effect record for Beta-sitosterol — expand a row for the licensed statement it rests on. We haven’t matched Interferon Beta-1a to its FDA label in our system yet, so we can’t compare its own side-effect list here — the leaflet that comes with your prescription is the authoritative list for Interferon Beta-1a.

Everything else you take

See Every Supplement That Interacts With Interferon Beta-1a

This page covers Beta-sitosterol only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Interferon Beta-1a 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 Beta-1a page

“Siberian cocklebur, an herb tied to documented cases of liver failure, is the first name to know for anyone injecting interferon beta-1a (Rebif, Avonex) for multiple sclerosis. Interferon beta-1a can strain the liver on its own, which is why prescribers order routine liver blood tests, and 38 of the 57 supplements on file carry that sa…”

Reviewed by 2 · Jul 18, 2026

Open the Interferon Beta-1a interaction page

One more smart check

Taking Beta-sitosterol as Part of a Dietary Supplement Product? Check It for Interactions

We hold 7 real supplement products containing Beta-sitosterol, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Beta-sitosterol. Even though Beta-sitosterol itself has no known interaction with Interferon Beta-1a, another ingredient on your label might. Find your product and we’ll check every ingredient on its label:

How much people look this up

Where Beta-sitosterol and Interferon Beta-1a 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 Beta-sitosterol
Top 25%

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

29 days ago today
Medication Interferon Beta-1a
Steady interest

#1,654 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.

Where does our data come from?
  • Source: the Natural Medicines (TRC Healthcare) clinical database — the evidence-graded professional reference for herb & supplement interactions.
  • Citation library: 103,510 references behind our interaction content, 65,311 of them resolved to verified PubMed/DOI sources. See every Beta-sitosterol reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Beta-sitosterol and Interferon Beta-1a records this page draws on were last updated July 10, 2026.
  • What “no known interaction” means: no documented interaction in the sources above — not a guarantee of safety. Supplements are studied far less than prescription drugs, so we say exactly what the evidence supports, and nothing more.
Data structure & sourcing designed and verified by .
Supplement

About Beta-sitosterol

What is Beta-sitosterol?

  • High cholesterol
  • Enlarged prostate (BPH)
  • Heart health
  • Immune support
  • Hair loss

Beta-sitosterol is a plant sterol that may modestly lower LDL ('bad') cholesterol and may help ease urinary symptoms from an enlarged prostate. Evidence is moderate for these uses and weaker for others, and it is generally well tolerated, but you should talk with your pharmacist or doctor before starting it.

Plant sterol found in seeds, nuts, vegetable oils, and many plants · Capsules, tablets, softgels, and fortified foods

An interaction check asks whether these two react with each other — it does not ask whether Beta-sitosterol is a good idea for someone in your situation. Here is what our Beta-sitosterol record says about it on its own.

Beta-sitosterol: dosing

There is no single official dose of beta-sitosterol for all uses. The amount used in studies varies depending on the condition being studied, and product strengths differ between brands.The best approach is to follow the directions on the product label and not take more than recommended.

From our Beta-sitosterol monograph — the full record covers uses, side effects and every documented interaction.

Read the full Beta-sitosterol monograph & all interactions
Medication

About Interferon Beta-1a Intramuscular Injection

What Is Interferon Beta-1a Intramuscular Injection Used For?

Brand names: Rebif, Avonex

  • Interferon beta-1a intramuscular injection is used to treat adults with various forms of multiple sclerosis (MS; a disease in which the nerves do not function properly and people may experience weakness, numbness, loss of muscle coordination, and problems with vision, speech, and bladder control) including:

    • clinically isolated syndrome (CIS; nerve symptom episodes that last at least 24 hours),

    • relapsing-remitting forms (course of disease where symptoms flare up from time to time), or

    • secondary progressive forms (course of disease where relapses occur more often).

  • Interferon beta-1a is in a class of medications called immunomodulators. It works by decreasing inflammation and preventing nerve damage that may cause symptoms of multiple sclerosis.

Most-Reported Side Effects for Interferon Beta-1a

From FAERS, the FDA’s public side-effect reporting system (192,069 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Multiple sclerosis relapse 15,851 reports
Influenza like illness 13,253 reports
Fatigue 11,554 reports
Fall 10,604 reports
Multiple sclerosis 9,358 reports
See full Interferon Beta-1a Intramuscular Injection drug information
Keep checking

Other Drugs & Beta-sitosterol

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

0Major
0Moderate
0Minor
2,829No known interaction
2,829 No interaction
No interaction 2,829 drugs checked — show the list

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

Showing the 60 most looked-up of 2,829 medications checked with no known interaction — see the full Beta-sitosterol list.

See the full Beta-sitosterol interactions page
See every supplement checked against Interferon Beta-1a, ranked by severity
Evidence & sources

Beta-sitosterol References

The 7 references that drive our Beta-sitosterol monograph and interaction data, from the evidence-graded Natural Medicines (TRC Healthcare) database. Citations with a link open the study on PubMed or the publisher’s site.

  1. Berges RR, Windeler J, Trampisch HJ, et al. Randomised, placebo-controlled, double-blind clinical trial of beta-sitosterol in patients with benign prostatic hyperplasia. Beta-sitosterol Study Group. Lancet 1995;345:1529-32.
  2. Klippel KF, Hiltl DM, Schipp B. A multicentric, placebo-controlled, double-blind clinical trial of beta-sitosterol (phytosterol) for the treatment of benign prostatic hyperplasia. Br J Urol 1997;80:427-32.
  3. Wilt TJ, MacDonald R, Ishani A. beta-sitosterol for the treatment of benign prostatic hyperplasia: a systematic review. BJU Int 1999;83:976-83. PubMed
  4. Oster P, Schlierf G, Heuck CC, et al. [Sitosterol in familial hyperlipoproteinemia type II. A randomized, double-blind, cross-over study]. Dtsch Med Wochenschr 1976;101:1308-11.
  5. Becker M, Staab D, Von Bergman K. Long-term treatment of severe familial hypercholesterolemia in children: effect of sitosterol and bezafibrate. Pediatrics 1992;89:138-42. DOI
  6. Prager N, Bickett K, French N, Marcovici G. A randomized, double-blind, placebo-controlled trial to determine the effectiveness of botanically derived inhibitors of 5-alpha-reductase in the treatment of androgenetic alopecia. J Altern Complement Med 2002
  7. Lorenze A, Hsueh W, Nasr J. Beta-sitosterol-induced acute pancreatitis: A case report and review of the literature. Cureus. 2020;12(3):e7407. PubMed

Medication overviews come from MedlinePlus (NIH); supplement label data from the NIH Dietary Supplement Label Database. Content is written and reviewed by licensed HelloPharmacist pharmacists — see our data sources and editorial standards.

Pharmacist Counseling Corner

Taking Beta-sitosterol and Interferon Beta-1a Together: Common Questions

Is it safe to take Beta-sitosterol with Interferon Beta-1a?
We do not list a known interaction between Beta-sitosterol and Interferon Beta-1a. That does not guarantee the combination is risk-free, so confirm with your pharmacist or doctor — especially if you take other medications or have a health condition.
Does Interferon Beta-1a interact with any supplements?
Yes. Interferon Beta-1a has documented interactions with 57 supplements in our database — Beta-sitosterol is not one of them. The Interferon Beta-1a interaction page linked on this page lists every one, ranked by severity.

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

Where next

Keep Exploring

Beta-sitosterol monograph Uses, safety profile, and every drug interaction in one place Interferon Beta-1a Intramuscular Injection drug information The full plain-English guide to this medication Interferon Beta-1a supplement interactions Every supplement checked against Interferon Beta-1a, ranked by severity Supplement interaction checker Check any supplement or product against your medications Browse medications A–Z Every drug we’ve checked against herbs & supplements References The 7 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Interferon Beta-1a and Beta-sitosterol?

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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.