Drug & supplement interaction

Algin + Peginterferon alfa-2a, Ribavirin

Peginterferon alfa-2a, Ribavirin brand names: Pegasys, Pegetron.

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

Algin has a minor interaction with Peginterferon alfa-2a, Ribavirin. Theoretically, algin can alter the absorption of oral drugs.

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

Algin and Peginterferon alfa-2a, Ribavirin

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

Minor

ORAL DRUGS

Why this applies to Peginterferon alfa-2a, Ribavirin

Peginterferon alfa-2a, Ribavirin falls under ORAL DRUGS — the group Algin interacts with.

Theoretically, algin can alter the absorption of oral drugs. Laboratory research shows that algin, when consumed as part of the diet or used as a thickening agent in infant formula, reduces the absorption of certain minerals. Also, algin has been used as a tablet binder and disintegrant to enhance drug bioavailability. To avoid changes in absorption, take algin 30-60 minutes after oral medications.
Severity Minor 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 practical angle for your hepatitis C treatment. Algin is a seaweed fiber that swells into a thick gel in your stomach, and in theory that gel could grab onto pills and slow how much of an oral medicine gets absorbed. With your regimen, the part that matters here is ribavirin, since that's the oral tablet or capsule. Peginterferon alfa-2a (Pegasys) is an injection, so algin in the gut wouldn't touch it.

I want to be honest about the strength of this: it's theoretical, based on lab work and how fiber behaves, not real cases of treatment failing. Still, ribavirin levels matter for clearing the virus, so a simple fix is to space them out. Take your ribavirin first, then wait 30 to 60 minutes before any algin product, and run it by your pharmacist.

Contact Dr. Brian directly if you have additional questions on this interaction
References
  1. Harmuth-Hoene, A. E. and Schelenz, R. Effect of dietary fiber on mineral absorption in growing rats. J Nutr 1980;110(9):1774-1784. PubMed
  2. Bosscher D, Van Caillie-Bertrand M, Deelstra H. Effect of thickening agents, based on soluble dietary fiber, on the availability of calcium, iron, and zinc from infant formulas. Nutrition. 2001;17(7-8):614-8. PubMed
  3. Beneke CE, Viljoen AM, Hamman JH. Polymeric plant-derived excipients in drug delivery. Molecules. 2009;14(7):2602-20. 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

Algin Also Interacts With Other Medications

Algin has 2,021 minor known drug interactions in our database — the Peginterferon alfa-2a, Ribavirin one above is one of them. If you take anything else, check it against the full list below.

Minor 2,021 No known interaction 809 (incl. Peginterferon alfa-2a, Ribavirin)
Taking anything else?

Check Another of Your Medications Against Algin

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

Everything else you take

See Every Supplement That Interacts With Peginterferon alfa-2a, Ribavirin

This page covers Algin only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Peginterferon alfa-2a, Ribavirin page lists 17 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Coffee Charcoal (moderate), European Mandrake (moderate), Glucomannan (moderate) and Guar Gum (moderate).

By severity: 1 major · 7 moderate · 9 minor.

From our pharmacist’s overview on the Peginterferon alfa-2a, Ribavirin page

“Hepatitis C treatment with Pegasys or Pegetron (peginterferon alfa-2a plus ribavirin) is rough on the stomach, and the charcoal, fiber powders, and soothing gums people reach for are exactly what fills this list. All 17 entries work the same way, interfering with how the oral ribavirin half of the therapy gets absorbed.”

Reviewed by 2 · Jul 18, 2026

Open the Peginterferon alfa-2a, Ribavirin interaction page

One more smart check

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

We hold 60 real supplement products containing Algin, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Algin. Your product may carry other ingredients that interact with Peginterferon alfa-2a, Ribavirin too, on top of Algin — 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 Algin and Peginterferon alfa-2a, Ribavirin 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 Algin
Top half

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

29 days ago today
Medication Peginterferon alfa-2a, Ribavirin
Top 5%

#74 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 Algin

What is Algin?

Algin
  • Heartburn and acid reflux (in combination products)
  • Lowering cholesterol
  • Digestive health and feeling full
  • Use as a thickener and binder in foods and medicines
  • Weight management

Algin (alginate) is a fiber-like substance from brown seaweed that is widely used as a thickener, gel, and binder in foods and medicines. Its best-known medical use is in heartburn products, where it forms a barrier that helps reduce acid reflux; evidence for other uses like lowering cholesterol or weight loss is weaker. It is generally considered safe in food amounts, but check with your pharmacist before using it as a supplement, especially if you are pregnant or breastfeeding.

Read the full Algin monograph & all interactions
Medication

About Peginterferon Alfa-2a Injection

What Is Peginterferon Alfa-2a Injection Used For?

Brand names: Pegasys, Pegetron

Pegasys (peginterferon alfa-2a) is used to treat chronic hepatitis C (CHC) and chronic hepatitis B (CHB). For chronic hepatitis C in adults, Pegasys is typically used in combination with other hepatitis C antiviral drugs; it may be used alone only if other HCV drugs cannot be tolerated or are contraindicated. For children aged 5 and older with CHC, Pegasys is used in combination with ribavirin.

For chronic hepatitis B, Pegasys treats adults who have HBeAg-positive or HBeAg-negative CHB with compensated liver disease and evidence of active viral replication and liver inflammation. In children aged 3 and older with HBeAg-positive CHB (without cirrhosis), Pegasys is also indicated when there is evidence of viral replication and liver enzyme elevation.

See full Peginterferon Alfa-2a Injection drug information
Keep checking

Other Drugs & Algin

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

0Major
0Moderate
2,021Minor
808No known interaction
2,021 Minor 808 No interaction
Minor

2,021 interactions

Showing 60 of 2,021 minor interactions — see all 2,021 on the Algin page.

No interaction 808 drugs checked — show the list

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

Showing the 60 most looked-up of 808 medications checked with no known interaction — see the full Algin list.

See the full Algin interactions page
See every supplement checked against Peginterferon alfa-2a, Ribavirin, 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
Algin monograph › Uses, safety, and every drug interaction in one place Peginterferon alfa-2a, Ribavirin supplement interactions › Every supplement checked against Peginterferon alfa-2a, Ribavirin, ranked by severity Peginterferon Alfa-2a 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 Algin and Peginterferon alfa-2a, Ribavirin Together: Common Questions

Can you take Algin with Peginterferon alfa-2a, Ribavirin?
There is only a minor interaction, which is usually not serious. Read the full details on this page and confirm with your pharmacist before combining them.
How serious is the Algin and Peginterferon alfa-2a, Ribavirin interaction?
We rate it Minor. This interaction is generally not clinically significant, but it remains worth noting and discussing with your pharmacist.

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

Still Have a Question About Peginterferon alfa-2a, Ribavirin and Algin?

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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.