Drug & supplement interaction

Alfalfa + Peginterferon alfa-2a

Peginterferon alfa-2a brand name: Pegasys IV.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between Alfalfa 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.

Know someone taking this? Share

Facebook Post Reddit Email

On this page

Interaction report

Alfalfa 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 Alfalfa 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.

Alfalfa safety at a glance

Alfalfa overall Use caution Generally considered food-safe in small amounts, but supplements and raw sprouts carry real risks for some people.

Pregnancy Possibly Unsafe When used orally in medicinal amounts. Alfalfa contains constituents with possible estrogenic activity. Read the full pregnancy detail

Breastfeeding Possibly Unsafe When used orally in medicinal amounts. Alfalfa contains constituents with possible estrogenic activity. Read the full breastfeeding detail

Pregnancy & breastfeeding ratings are from Natural Medicines (Therapeutic Research Center) — the full detail is in the Special populations card below. Safety guidance is general; always confirm with your pharmacist or doctor for your situation.

Still wondering about combining Peginterferon alfa-2a and Alfalfa? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

Keep it in perspective

Alfalfa Does Interact With Other Medications

Alfalfa has 2 major, 581 moderate 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.

Major 2 Moderate 581 No known interaction 2,247 (incl. Peginterferon alfa-2a)

Taking anything else?

Check Another of Your Medications Against Alfalfa

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

What to actually watch for

No Interaction Found — But Data Suggests Alfalfa 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.

A higher chance of infection Worth acting on Additional detail
Alfalfa
“Alfalfa products, including sprouts, seeds, and tablets, have been found to be contaminated with Escherichia coli, Salmonella, and Listeria monocytogenes, which have caused documented infections.

Orally, alfalfa has been associated with the development of a lupus-like syndrome in animals and humans, as well as with possible exacerbations of lupus in patients with known systemic lupus erythematosus (SLE).”

Alfalfa · Natural Medicines adverse-effect record, reported in systemic lupus erythematosus (sle).
6 sources cited

5600. Farber JM, Carter AO, Varughese PV, et al. Listeriosis traced to the consumption of alfalfa tablets and soft cheese [Letter to the Editor]. N Engl J Med 1990;322:338. PubMed

30566. Mohle-Boetani J, Werner B, Polumbo M, and et al. From the Centers for Disease Control and Prevention. Alfalfa sprouts-- Arizona, California, Colorado, and New Mexico, February-April, 2001. JAMA 2-6-2002;287(5):581-582.

30568. Howard, M. B. and Hutcheson, S. W. Growth dynamics of Salmonella enterica strains on alfalfa sprouts and in waste seed irrigation water. Appl.Environ.Microbiol. 2003;69(1):548-553.

30572. Strapp, C. M., Shearer, A. E., and Joerger, R. D. Survey of retail alfalfa sprouts and mushrooms for the presence of Escherichia coil O157:H7, Salmonella, and Listeria with BAX, and evaluation of this polymerase chain reaction-based system with experimen

30569. Winthrop, K. L., Palumbo, M. S., Farrar, J. A., Mohle-Boetani, J. C., Abbott, S., Beatty, M. E., Inami, G., and Werner, S. B. Alfalfa sprouts and Salmonella Kottbus infection: a multistate outbreak following inadequate seed disinfection with heat and chl

30564. Backer, H. D., Mohle-Boetani, J. C., Werner, S. B., Abbott, S. L., Farrar, J., and Vugia, D. J. High incidence of extra-intestinal infections in a Salmonella Havana outbreak associated with alfalfa sprouts. Public Health Rep. 2000;115(4):339-345. PubMed
Peginterferon alfa-2a

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

Alfalfa

Recorded for Alfalfa in the same Natural Medicines adverse-effect record shown under A higher chance of infection above.

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
Alfalfa
“Orally, flatulence and bulkier feces were reported during the first week of a case series of three subjects ingesting alfalfa. In a case series of 15 patients ingesting alfalfa, increased fecal volume and increased stool frequency was reported. Additional adverse effects included abdominal discomfort in two patients, diarrhea in two patients, loose stools in six patients, and intestinal gas in 13 patients.”

Alfalfa · Natural Medicines adverse-effect record, reported in diarrhea.
2 sources cited

30598. Malinow, M. R., McLaughlin, P., and Stafford, C. Alfalfa seeds: effects on cholesterol metabolism. Experientia 5-15-1980;36(5):562-564. PubMed

5816. Molgaard J, von Schenck H, Olsson AG. Alfalfa seeds lower low density lipoprotein cholesterol and apolipoprotein B concentrations in patients with type II hyperlipoproteinemia. Atherosclerosis 1987;65:173-9. PubMed
Peginterferon alfa-2a

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

Reported for Alfalfa but not commonly for Peginterferon alfa-2a: bloating or gas, low potassium, a skin rash and swelling.

Effects for Peginterferon alfa-2a come from the ADVERSE REACTIONS section of its FDA label; effects for Alfalfa 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.

Special populations

Alfalfa in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Unsafe

When used orally in medicinal amounts. Alfalfa contains constituents with possible estrogenic activity.

DISCLAIMER: This tool is intended for informational purposes only, and should not be interpreted as specific medical advice. Patients should consult with a qualified healthcare provider before making decisions about therapies and/or health conditions.© 2026 Therapeutic Research Center

From our Q&A

Questions About Alfalfa or Peginterferon alfa-2a

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Alfalfa or Peginterferon alfa-2a, 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:

Can Licorice Or Alfalfa Affect Birth Control Pills? Answered by Dr. Brian Staiger, PharmD · August 2022 ›

Not quite your question? Ask our pharmacists directly — it is free, there is no account required, and answers usually come back within 24 hours.

One more smart check

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

We hold 3,559 real supplement products containing Alfalfa, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Alfalfa. Even though Alfalfa 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 Alfalfa 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 Alfalfa

Top 10%

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

29 days ago today

Medication Peginterferon alfa-2a

Top 25%

#493 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 Alfalfa reference on this page ↓
Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Alfalfa 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 Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Alfalfa

What is Alfalfa?

High cholesterol
Digestive complaints
Menopausal symptoms
Arthritis and joint pain
General nutritional supplement

Alfalfa is a nutrient-rich legume that people use for high cholesterol, menopause symptoms, and general wellness, but solid human evidence for most of these uses is limited. It is best avoided by people with autoimmune diseases, those who are pregnant or breastfeeding, and anyone with a weakened immune system, and you should check with your pharmacist or doctor before trying it.

Medicago sativa · Fabaceae · Leaves, sprouts, and seeds · Capsules, tablets, dried leaf tea, sprouts, liquid extract, and powder

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

Alfalfa: dosing

There is no well-established standard dose for alfalfa supplements. Products vary widely in strength and form, including capsules, tablets, teas, and extracts.Because a proven safe and effective dose has not been set, the best approach is to follow the directions on the product label and not exceed the recommended amount. They can help you decide if it is appropriate for you.

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

Read the full Alfalfa 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 & Alfalfa

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

2Major

581Moderate

0Minor

2,246No known interaction

2 Major 581 Moderate 2,246 No interaction

Major

2 interactions

Moderate

581 interactions

Showing 60 of 581 moderate interactions — see all 581 on the Alfalfa page.

No interaction 2,246 drugs checked — show the list

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

Showing the 60 most looked-up of 2,246 medications checked with no known interaction — see the full Alfalfa list.

See the full Alfalfa interactions page

See every supplement checked against Peginterferon alfa-2a, ranked by severity

Evidence & sources

Alfalfa References

The 32 references that drive our Alfalfa 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.

Newall CA, Anderson LA, Philpson JD. Herbal Medicine: A Guide for Healthcare Professionals. London, UK: The Pharmaceutical Press, 1996.
The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
Kurzer MS, Xu X. Dietary phytoestrogens. Annu Rev Nutr 1997;17:353-81. PubMed
Farber JM, Carter AO, Varughese PV, et al. Listeriosis traced to the consumption of alfalfa tablets and soft cheese [Letter to the Editor]. N Engl J Med 1990;322:338. PubMed
Molgaard J, von Schenck H, Olsson AG. Alfalfa seeds lower low density lipoprotein cholesterol and apolipoprotein B concentrations in patients with type II hyperlipoproteinemia. Atherosclerosis 1987;65:173-9. PubMed
Light TD, Light JA. Acute renal transplant rejection possibly related to herbal medications. Am J Transplant 2003;3:1608-9. PubMed
Prete PE. The mechanism of action of L-canavanine in inducing autoimmune phenomena. Arthritis Rheum 1985;28:1198-200. PubMed
Alcocer-Varela J, Iglesias A, Llorente L, Alarcon-Segovia D. Effects of L-canavanine on T cells may explain the induction of systemic lupus erythematosus by alfalfa. Arthritis Rheum 1985;28:52-7. PubMed
Roberts JL, Hayashi JA. Exacerbation of SLE associated with alfalfa ingestion. N Engl J Med 1983;308:1361. DOI
Feingold, R. M. Should we fear "health foods"? Arch Intern Med 7-12-1999;159(13):1502. PubMed
Taormina, P. J., Beuchat, L. R., and Slutsker, L. Infections associated with eating seed sprouts: an international concern. Emerg.Infect.Dis 1999;5(5):626-634. PubMed
Backer, H. D., Mohle-Boetani, J. C., Werner, S. B., Abbott, S. L., Farrar, J., and Vugia, D. J. High incidence of extra-intestinal infections in a Salmonella Havana outbreak associated with alfalfa sprouts. Public Health Rep. 2000;115(4):339-345. PubMed
Mohle-Boetani J, Werner B, Polumbo M, and et al. From the Centers for Disease Control and Prevention. Alfalfa sprouts-- Arizona, California, Colorado, and New Mexico, February-April, 2001. JAMA 2-6-2002;287(5):581-582.
Howard, M. B. and Hutcheson, S. W. Growth dynamics of Salmonella enterica strains on alfalfa sprouts and in waste seed irrigation water. Appl.Environ.Microbiol. 2003;69(1):548-553.
Winthrop, K. L., Palumbo, M. S., Farrar, J. A., Mohle-Boetani, J. C., Abbott, S., Beatty, M. E., Inami, G., and Werner, S. B. Alfalfa sprouts and Salmonella Kottbus infection: a multistate outbreak following inadequate seed disinfection with heat and chl
Strapp, C. M., Shearer, A. E., and Joerger, R. D. Survey of retail alfalfa sprouts and mushrooms for the presence of Escherichia coil O157:H7, Salmonella, and Listeria with BAX, and evaluation of this polymerase chain reaction-based system with experimen
Akaogi, J., Barker, T., Kuroda, Y., Nacionales, D. C., Yamasaki, Y., Stevens, B. R., Reeves, W. H., and Satoh, M. Role of non-protein amino acid L-canavanine in autoimmunity. Autoimmun.Rev 2006;5(6):429-435. PubMed
Burden and causes of foodborne disease in Australia: Annual report of the OzFoodNet network, 2005. Commun.Dis Intell. 2006;30(3):278-300.
Shemesh, M., Lindner, H. R., and Ayalon, N. Affinity of rabbit uterine oestradiol receptor for phyto-oestrogens and its use in a competitive protein-binding radioassay for plasma coumestrol. J Reprod.Fertil. 1972;29(1):1-9. PubMed
Elakovich, S. D. and Hampton, J. M. Analysis of coumestrol, a phytoestrogen, in alfalfa tablets sold for human consumption. J Agric.Food Chem. 1984;32(1):173-175. PubMed
Malinow, M. R., Bardana, E. J., Jr., Pirofsky, B., Craig, S., and McLaughlin, P. Systemic lupus erythematosus-like syndrome in monkeys fed alfalfa sprouts: role of a nonprotein amino acid. Science 4-23-1982;216(4544):415-417. PubMed
Malinow, M. R., McLaughlin, P., and Stafford, C. Alfalfa seeds: effects on cholesterol metabolism. Experientia 5-15-1980;36(5):562-564. PubMed
Farnsworth, N. R. Alfalfa pills and autoimmune diseases. Am J Clin Nutr. 1995;62(5):1026-1028. DOI
Herbert, V. and Kasdan, T. S. Alfalfa, vitamin E, and autoimmune disorders. Am J Clin Nutr 1994;60(4):639-640.
Mahon, B. E., Ponka, A., Hall, W. N., Komatsu, K., Dietrich, S. E., Siitonen, A., Cage, G., Hayes, P. S., Lambert-Fair, M. A., Bean, N. H., Griffin, P. M., and Slutsker, L. An international outbreak of Salmonella infections caused by alfalfa sprouts grow
Gray, A. M. and Flatt, P. R. Pancreatic and extra-pancreatic effects of the traditional anti- diabetic plant, Medicago sativa (lucerne). Br J Nutr. 1997;78(2):325-334.
Van Beneden, C. A., Keene, W. E., Strang, R. A., Werker, D. H., King, A. S., Mahon, B., Hedberg, K., Bell, A., Kelly, M. T., Balan, V. K., Mac Kenzie, W. R., and Fleming, D. Multinational outbreak of Salmonella enterica serotype Newport infections due to
Rubenstein AH, Levin NW, and Elliott GA. Manganese-induced hypoglycemia. Lancet 1962;1348-1351.
Kaufman W. Alfalfa seed dermatitis. JAMA 1954;155(12):1058-1059. PubMed
Ponka A, Andersson Y, Siitonen A, and et al. Salmonella in alfalfa sprouts. Lancet 1995;345:462-463. PubMed
Puschner B, Chen X, Read D, Affolter VK. Alfalfa hay induced primary photosensitization in horses. Vet J. 2016 May;211:32-8. 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 Alfalfa and Peginterferon alfa-2a Together: Common Questions

Is it safe to take Alfalfa with Peginterferon alfa-2a?

We do not list a known interaction between Alfalfa 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 Alfalfa and Peginterferon alfa-2a have any of the same side effects?

Yes — our sources link each of them separately to 4 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.

Does Alfalfa interact with any other medications?

Yes. Alfalfa has 583 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

Alfalfa 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 32 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Peginterferon alfa-2a and Alfalfa?

Our pharmacists answer your medication & supplement questions — free.

Ask a pharmacist

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.