Drug & supplement interaction

Cordyceps + Peginterferon alfa-2a

Peginterferon alfa-2a brand name: Pegasys IV.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Cordyceps and Peginterferon alfa-2a 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. Additionally, although there is no interaction, the two are separately associated with some of the same side effects, which would make a new symptom harder to attribute to one or the other.

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Interaction report

Cordyceps and Peginterferon alfa-2a

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 Peginterferon alfa-2a and Cordyceps 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.

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.

Cordyceps safety at a glance

Cordyceps overall Use caution Generally well tolerated short-term, but evidence is limited and product quality varies widely.
Pregnancy Avoid Not enough safety data, so it is best avoided during pregnancy.
Breastfeeding Avoid Not enough safety data, so it is best avoided while breastfeeding.

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

Still wondering about combining Peginterferon alfa-2a and Cordyceps? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
Keep it in perspective

Cordyceps Does Interact With Other Medications

Cordyceps has 241 moderate, 8 minor known drug interactions in our database — Peginterferon alfa-2a isn’t one of them. If you take anything else, check it against the full list below.

Moderate 241 Minor 8 No known interaction 2,581 (incl. Peginterferon alfa-2a)
Taking anything else?

Check Another of Your Medications Against Cordyceps

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

What to actually watch for

No Interaction Found — But Data Suggests Cordyceps and Peginterferon alfa-2a May Share Several of the Same Side Effects

This is not an interaction. Neither one changes how your body handles the other, and nothing here says they react together. What our sources do show is that each has separately been linked to the effects below — so taking both can make those effects more likely to turn up, and harder to pin on one or the other if they do. One of them is worth acting on rather than waiting out — marked below.

  • Liver problems Worth acting on Additional detail

    Cordyceps

    “There is a case report of acute cholestatic hepatitis probably associated with the use of a product containing cordyceps. The 64-year-old male was asymptomatic except for jaundice and laboratory markers and recovered once the supplement was stopped. However, it is unclear whether the hepatitis is associated with the cordyceps or with an unknown contaminant.”

    Cordyceps · Natural Medicines adverse-effect record, reported in hepatitis.

    1 source cited
    1. 109704. Thurian D, Montani M, Stickel F. Drug-induced, mixed-type hepatitis following ingestion of Cordyceps sinensis. Int J Clin Pharmacol Ther 2022;60(2):115-120. PubMed

    Peginterferon alfa-2a

    Listed in the ADVERSE REACTIONS section of the FDA label for Peginterferon alfa-2a. Read the label on DailyMed ›

  • Dry mouth Additional detail

    Cordyceps

    “Orally, cordyceps has been associated with diarrhea, constipation, abdominal discomfort, dry mouth, and throat discomfort in clinical research. However, these events were uncommon, and in some cases symptoms could be reduced by taking cordyceps after eating.”

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

    3 sources cited
    1. 92829. Zhang HW, Lin ZX, Tung YS, Kwan TH, Mok CK, Leung C, Chan LS. Cordyceps sinensis (a traditional Chinese medicine) for treating chronic kidney disease (Review). Cochrane Database Syst Rev. 2014;(12):CD008353. doi: 10.1002/14651858.CD008353.pub2. PubMed
    2. 105076. Bee Yean O, Zoriah A. Efficacy of Cordyceps sinensis as an adjunctive treatment in hemodialysis patients: a systematic review and Meta-analysis. J Tradit Chin Med. 2019;39(1):1-14.
    3. 109705. Yu X, Mao Y, Shergis JL, et al. Effectiveness and safety of oral Cordyceps sinensis on stable COPD of GOLD stages 2-3: Systematic review and meta-analysis. Evid Based Complement Alternat Med. 2019;2019:4903671.

    Peginterferon alfa-2a

    Listed in the ADVERSE REACTIONS section of the FDA label for Peginterferon alfa-2a. Read the label on DailyMed ›

  • Reduced appetite Additional detail

    Cordyceps

    “Two cases of lead poisoning, characterized by loss of appetite and other symptoms, have been reported for patients taking cordyceps powder. After discontinuing cordyceps supplementation, both patients were treated with chelating agents.”

    Cordyceps · Natural Medicines adverse-effect record, reported in poisoning.

    1 source cited
    1. 46135. Wu, T. N., Yang, K. C., Wang, C. M., Lai, J. S., Ko, K. N., Chang, P. Y., and Liou, S. H. Lead poisoning caused by contaminated Cordyceps, a Chinese herbal medicine: two case reports. Sci.Total Environ. 4-5-1996;182(1-3):193-195. PubMed

    Peginterferon alfa-2a

    Listed in the ADVERSE REACTIONS section of the FDA label for Peginterferon alfa-2a. Read the label on DailyMed ›

  • Stomach upset / Diarrhea Additional detail

    Cordyceps

    “Orally, cordyceps seems to be generally well tolerated when used for up to 1 year.

    Most Common Adverse Effects:

    Orally: Abdominal discomfort, constipation, diarrhea.”

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

    Peginterferon alfa-2a

    Listed in the ADVERSE REACTIONS section of the FDA label for Peginterferon alfa-2a. Read the label on DailyMed ›

Reported for Cordyceps but not commonly for Peginterferon alfa-2a: constipation and yellowing of the skin or eyes.

Effects for Peginterferon alfa-2a come from the ADVERSE REACTIONS section of its FDA label; effects for Cordyceps come from the Natural Medicines adverse-effect record, quoted above. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Overlapping uses

What Peginterferon alfa-2a Is Prescribed For, and What Cordyceps Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Peginterferon alfa-2a is a prescription medicine with approved uses on its FDA label. Cordyceps is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Peginterferon alfa-2a is prescribed for: 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.

Read the rest of what Peginterferon alfa-2a is prescribed for

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.

Cordyceps has been studied for:

  • Hepatitis B studied, not established Cordyceps has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Cordyceps for hepatitis b

    Although there is interest in using oral cordyceps for hepatitis B, there is insufficient reliable information about the clinical effects of cordyceps for this condition.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Peginterferon alfa-2a on your own; if you are taking Cordyceps for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

One more smart check

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

We hold 2,140 real supplement products containing Cordyceps, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Cordyceps. Even though Cordyceps itself has no known interaction with Peginterferon alfa-2a, 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 Cordyceps and Peginterferon alfa-2a 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 Cordyceps
Top 10%

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

29 days ago today
Medication Peginterferon alfa-2a
Top 25%

#494 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 Cordyceps reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Cordyceps and Peginterferon alfa-2a 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 Cordyceps

What is Cordyceps?

Cordyceps
  • Fatigue and low energy
  • Athletic performance and stamina
  • Respiratory and lung support
  • Immune support
  • Kidney health support
  • General wellness/anti-aging

Cordyceps is a fungus used in traditional Chinese medicine for energy, exercise performance, and lung and immune support. Human research is limited and mostly low quality, so its benefits are not well proven. It appears generally well tolerated in the short term, but quality varies and it should be avoided in pregnancy and breastfeeding due to lack of safety data.

Ophiocordyceps sinensis · Ophiocordycipitaceae · Whole fungus (fruiting body and mycelium), often grown in culture as the Cs-4 strain · Capsules, tablets, powders, extracts, teas, and tinctures

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

Cordyceps: dosing

There is no official or standardized dose for cordyceps. Doses used in studies have varied widely depending on the product, species, and extract type.The best approach is to follow the directions on the product label and not exceed the recommended amount.

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

Read the full Cordyceps monograph & all interactions
Medication

About Peginterferon Alfa-2a Injection

What Is Peginterferon Alfa-2a Injection Used For?

Brand name: Pegasys IV

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 & Cordyceps

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

0Major
241Moderate
8Minor
2,580No known interaction
241 Moderate 8 Minor 2,580 No interaction
Moderate

241 interactions

Showing 60 of 241 moderate interactions — see all 241 on the Cordyceps page.

Minor

8 interactions

No interaction 2,580 drugs checked — show the list

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

Showing the 60 most looked-up of 2,580 medications checked with no known interaction — see the full Cordyceps list.

See the full Cordyceps interactions page
See every supplement checked against Peginterferon alfa-2a, ranked by severity
Evidence & sources

Cordyceps References

The 14 references that drive our Cordyceps 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. Zhu JS, Halpern GM, Jones K. The scientific rediscovery of an ancient Chinese herbal medicine: Cordyceps sinensis: part I. J Altern Complement Med 1998;4:289-303.
  2. Zhu JS, Halpern GM, Jones K. The scientific rediscovery of a precious ancient Chinese herbal regimen: Cordyceps sinensis: part II. J Altern Complement Med 1998;4:429-57.
  3. Chen YJ, Shiao MS, Lee SS, Wang SY. Effect of Cordyceps sinensis on the proliferation and differentiation of human leukemic U937 cells. Life Sci 1997;60:2349-59. PubMed
  4. Zhao Y. [Inhibitory effects of alcoholic extract of Cordyceps sinensis on abdominal aortic thrombus formation in rabbits]. Chung Hua I Hsueh Tsa Chih (Taipei) 1991;71:612-5, 42.
  5. Chen GZ, Chen GL, Sun T, et al. Effects of Cordyceps sinensis on murine T lymphocyte subsets. Chin Med J (English) 1991;104:4-8.
  6. Zhu XY, Yu HY. [Immunosuppressive effect of cultured Cordyceps sinensis on cellular immune response]. Chung Hsi I Chieh Ho Tsa Chih 1990;10:485-7, 454.
  7. Hsu, C. C., Huang, Y. L., Tsai, S. J., Sheu, C. C., and Huang, B. M. In vivo and in vitro stimulatory effects of Cordyceps sinensis on testosterone production in mouse Leydig cells. Life Sci 9-5-2003;73(16):2127-2136. PubMed
  8. Ikumoto, T., Sasaki, S., Namba, H., Toyama, R., Moritoki, H., and Mouri, T. [Physiologically active compounds in the extracts from tochukaso and cultured mycelia of Cordyceps and Isaria]. Yakugaku Zasshi 1991;111(9):504-509. PubMed
  9. Wu, T. N., Yang, K. C., Wang, C. M., Lai, J. S., Ko, K. N., Chang, P. Y., and Liou, S. H. Lead poisoning caused by contaminated Cordyceps, a Chinese herbal medicine: two case reports. Sci.Total Environ. 4-5-1996;182(1-3):193-195. PubMed
  10. Hong T, Zhang M, Fan J. Cordyceps sinensis (a traditional Chinese medicine) for kidney transplant recipients (Review). Cochrane Database Syst Rev. 2015;(10):CD009698. doi: 10.1002/14651858.CD009698.pub2.
  11. Zhang HW, Lin ZX, Tung YS, Kwan TH, Mok CK, Leung C, Chan LS. Cordyceps sinensis (a traditional Chinese medicine) for treating chronic kidney disease (Review). Cochrane Database Syst Rev. 2014;(12):CD008353. doi: 10.1002/14651858.CD008353.pub2. PubMed
  12. Bee Yean O, Zoriah A. Efficacy of Cordyceps sinensis as an adjunctive treatment in hemodialysis patients: a systematic review and Meta-analysis. J Tradit Chin Med. 2019;39(1):1-14.
  13. Thurian D, Montani M, Stickel F. Drug-induced, mixed-type hepatitis following ingestion of Cordyceps sinensis. Int J Clin Pharmacol Ther 2022;60(2):115-120. PubMed
  14. Yu X, Mao Y, Shergis JL, et al. Effectiveness and safety of oral Cordyceps sinensis on stable COPD of GOLD stages 2-3: Systematic review and meta-analysis. Evid Based Complement Alternat Med. 2019;2019:4903671.

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 Cordyceps and Peginterferon alfa-2a Together: Common Questions

Is it safe to take Cordyceps with Peginterferon alfa-2a?
We do not list a known interaction between Cordyceps and Peginterferon alfa-2a. 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.
Do Cordyceps and Peginterferon alfa-2a have any of the same side effects?
Yes — our sources link each of them separately to 5 of the same effects. That is not an interaction: neither changes how your body handles the other. It does mean that if one of those effects turns up, it can be harder to tell which one is behind it. They are listed on this page with the source behind each.
Are Cordyceps and Peginterferon alfa-2a used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Cordyceps in each. That is a conversation for your prescriber, especially if Peginterferon alfa-2a is being adjusted to a target.
Does Cordyceps interact with any other medications?
Yes. Cordyceps has 249 documented drug interactions in our database — Peginterferon alfa-2a is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.

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

Where next

Keep Exploring

Cordyceps monograph Uses, safety profile, and every drug interaction in one place Peginterferon Alfa-2a Injection drug information The full plain-English guide to this medication Peginterferon alfa-2a supplement interactions Every supplement checked against Peginterferon alfa-2a, 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 14 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

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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.