Drug & supplement interaction

Calcium + Interferon Alfa-2b

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

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 Calcium and Interferon Alfa-2b 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

Calcium and Interferon Alfa-2b

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 Alfa-2b and Calcium 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.

Calcium safety at a glance

Calcium overall Generally safe Generally safe when taken at recommended amounts, but high doses can cause problems.
Pregnancy Likely Safe When used orally and appropriately. The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy t... Read the full pregnancy detail
Breastfeeding Likely Safe When used orally and appropriately. The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy t... 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 Interferon Alfa-2b and Calcium? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Interferon Alfa-2b

Interactions in our licensed database are recorded against drug classes, not just single drug names. Interferon Alfa-2b is filed under 2 classifications — photosensitizing drugs, hepatotoxic drugs. Calcium has documented interactions with 18 drug classes — the most serious being ceftriaxone (rocephin) (major), dolutegravir (tivicay) (major) and elvitegravir (vitekta) (major) — and none of Interferon Alfa-2b’s classifications are among them.

Classification data comes from our licensed Natural Medicines dataset. A medication can belong to classes beyond those recorded there, so this describes how the check was run — it is not a safety guarantee.

Keep it in perspective

Calcium Does Interact With Other Medications

Calcium has 7 major, 143 moderate, 18 minor known drug interactions in our database — Interferon Alfa-2b isn’t one of them. If you take anything else, check it against the full list below.

Major 7 Moderate 143 Minor 18 No known interaction 2,662 (incl. Interferon Alfa-2b)
Taking anything else?

Check Another of Your Medications Against Calcium

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

What to actually watch for

What Calcium Itself Has Been Linked To

This is not an interaction — nothing below involves Interferon Alfa-2b. It is the side-effect record for Calcium on its own, from the licensed Natural Medicines monograph. If something new turns up after you add Calcium, this list is the first place to look. 2 entries are worth acting on rather than waiting out — marked below.

  • Kidney stones Worth acting on Additional detail

    “Kidney stones have been reported in individuals taking calcium carbonate 1500 mg daily in combination with vitamin D 2000 IU daily for 4 years.”

    Calcium · Natural Medicines adverse-effect record, reported in kidney stones (nephrolithiasis).

    1 source cited
    1. 93943. Lappe J, Watson P, Travers-Gustafson D, Recker R, Garland C, Gorham E, Baggerly K, McDonnell SL. Effect of Vitamin D and Calcium Supplementation on Cancer Incidence in Older Women: A Randomized Clinical Trial. JAMA. 2017 Mar 28;317(12):1234-1243. PubMed
  • Bone thinning / A heart attack / A severe skin reaction / Kidney problems / A higher chance of infection Worth acting on Additional detail

    “There has been concern that calcium intake may be associated with an increased risk of cardiovascular disease (CVD) and coronary heart disease (CHD), including myocardial infarction (MI). Some clinical research suggests that calcium intake, often in amounts over the recommended daily intake level of 1000-1300 mg daily for adults, is associated with an increased risk of CVD, CHD, and MI.”

    Calcium · Natural Medicines adverse-effect record, reported in cardiovascular disease (cvd).

    6 sources cited
    1. 16118. Bolland MJ, Barber PA, Doughty RN, et al. Vascular events in healthy older women receiving calcium supplementation: randomised control trial. BMJ 2008;336:262-6.
    2. 17482. Bolland MJ, Avenell A, Baron JA, et al. Effect of calcium supplements on risk of myocardial infarction and cardiovascular events: meta-analysis. BMJ 2010;341:c3691. PubMed
    3. 91350. Li K, Kaaks R, Linseisen J, Rohrmann S. Associations of dietary calcium intake and calcium supplementation with myocardial infarction and stroke risk and overall cardiovascular mortality in the Heidelberg cohort of the European Prospective Investigation i
    4. 107233. Myung SK, Kim HB, Lee YJ, Choi YJ, Oh SW. Calcium Supplements and Risk of Cardiovascular Disease: A Meta-Analysis of Clinical Trials. Nutrients 2021;13(2):368. PubMed
    5. 94137. Grove ML, Cook D. Calcium and heart attacks. Doesn't apply to most calcium prescriptions. BMJ. 2010;341:c5003. PubMed
    6. 92994. Chung M, Tang AM, Fu Z. Calcium Intake and Cardiovascular Disease Risk: An Updated Systematic Review and Meta-analysis. Ann Intern Med. 2016 Oct 25. PubMed
  • Bloating or gas / Stomach upset / Constipation / Diarrhea Additional detail

    “Orally, calcium can cause belching, flatulence, nausea, gastrointestinal discomfort, and diarrhea. Although constipation is frequently cited as an adverse effect of calcium, there is no scientific substantiation of this side effect. Calcium carbonate has been reported to cause acid rebound, but this is controversial.”

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

    6 sources cited
    1. 1824. Thys-Jacobs S, Ceccarelli S, Bierman A, et al. Calcium supplementation in premenstrual syndrome: a randomized crossover trial. J Gen Intern Med 1989;4:183-9. PubMed
    2. 1843. Maton PN, Burton ME. Antacids revisited: a review of their clinical pharmacology and recommended therapeutic use. Drugs 1999;57:855-70.
    3. 12950. Weingarten MA, Zalmanovici A, Yaphe J. Dietary calcium supplementation for preventing colorectal cancer and adenomatous polyps. Cochrane Database Syst Rev 2004;(1):CD003548. PubMed
    4. 38803. Dickinson, H. O., Nicolson, D. J., Cook, J. V., Campbell, F., Beyer, F. R., Ford, G. A., and Mason, J. Calcium supplementation for the management of primary hypertension in adults. Cochrane.Database.Syst.Rev. 2006;(2):CD004639. PubMed
    5. 1844. Clemens JD, Feinstein AR. Calcium carbonate and constipation: a historical review of medical mythopoeia. Gastroenterology 1977;72:957-61. DOI
    6. 1845. Saunders D, Sillery J, Chapman R. Effect of calcium carbonate and aluminum hydroxide on human intestinal function. Dig Dis Sci 1988;33:409-13. PubMed

Showing the 10 most notable of 11 recorded effects — ranked by how unusual each one is across medicines generally, with serious effects weighted up.

Everything above comes from the Natural Medicines adverse-effect record for Calcium — expand a row for the licensed statement it rests on. We haven’t matched Interferon Alfa-2b 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 Alfa-2b.

Special populations

Calcium in Pregnancy & Breastfeeding

Pregnancy And Lactation Likely Safe

When used orally and appropriately. The World Health Organization (WHO) recommends prescribing oral calcium supplementation 1.5-2 grams daily during pregnancy to those with low dietary calcium intake to prevent pre-eclampsia.

Pregnancy And Lactation Possibly Unsafe

When used orally in excessive doses. The Institute of Medicine sets the same daily tolerable upper intake level (UL) for calcium according to age independent of pregnancy status: 9-18 years, 3000 mg; 19-50 years, 2500 mg. Doses over these amounts might increase the risk of neonatal hypocalcemia-induced seizures possibly caused by transient neonatal hypoparathyroidism in the setting of excessive calcium supplementation during pregnancy, especially during the third trimester. Neonatal hypocalcemia is a risk factor for neonatal seizures.

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 Calcium or Interferon Alfa-2b

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

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

Everything else you take

See Every Supplement That Interacts With Interferon Alfa-2b

This page covers Calcium 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 Calcium as Part of a Dietary Supplement Product? Check It for Interactions

We hold 38,397 real supplement products containing Calcium, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Calcium. Even though Calcium itself has no known interaction with Interferon Alfa-2b, 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 Calcium 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 Calcium
Most looked up

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

29 days ago today
Medication Interferon Alfa-2b
Steady interest

#1,557 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 Calcium reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Calcium and Interferon Alfa-2b 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 Calcium

What is Calcium?

  • Bone health and osteoporosis prevention
  • Dietary calcium deficiency
  • Heartburn relief (calcium carbonate antacids)
  • Supporting healthy teeth
  • High blood pressure support during pregnancy

Calcium is an essential mineral your body needs for strong bones, nerve signaling, and muscle function, and supplements can help fill gaps when diet falls short. Most people do best getting calcium from food, and supplements should be used at the lowest dose needed. Talk to your pharmacist or doctor before starting, especially if you have kidney problems or take other medicines.

Mineral (not a plant part) · Tablets, capsules, chewable tablets, liquids, powders; common salts include calcium carbonate and calcium citrate

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

Calcium: dosing

The right amount of calcium depends on your age, sex, diet, and health needs. Recommended daily amounts are set by health authorities and generally increase with age, especially for older women. There are also upper limits that should not be exceeded without medical advice. Because needs vary, this monograph does not list specific milligram amounts.A few practical tips: your body absorbs calcium best when you take no more than about 500 to 600 mg at one time, so larger daily amounts are usually split into separate doses. Calcium carbonate should be taken with food, while calcium citrate can be taken with or without food.

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

Read the full Calcium 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 & Calcium

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

7Major
143Moderate
18Minor
2,661No known interaction
7 Major 143 Moderate 18 Minor 2,661 No interaction
Major

7 interactions

Moderate

143 interactions

Showing 60 of 143 moderate interactions — see all 143 on the Calcium page.

Minor

18 interactions

No interaction 2,661 drugs checked — show the list

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

Showing the 60 most looked-up of 2,661 medications checked with no known interaction — see the full Calcium list.

See the full Calcium interactions page
See every supplement checked against Interferon Alfa-2b, ranked by severity
Evidence & sources

Calcium References

The 62 references that drive our Calcium 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. Shils M, Olson A, Shike M. Modern Nutrition in Health and Disease. 8th ed. Philadelphia, PA: Lea and Febiger, 1994.
  2. Hernandez-Avila M, Gonzalez-Cossio T, Hernandez-Avila JE, et al. Dietary calcium supplements to lower blood lead levels in lactating women: a randomized placebo-controlled trial. Epidemiology 2003;14:206-12.. PubMed
  3. Thys-Jacobs S, Ceccarelli S, Bierman A, et al. Calcium supplementation in premenstrual syndrome: a randomized crossover trial. J Gen Intern Med 1989;4:183-9. PubMed
  4. Maton PN, Burton ME. Antacids revisited: a review of their clinical pharmacology and recommended therapeutic use. Drugs 1999;57:855-70.
  5. Clemens JD, Feinstein AR. Calcium carbonate and constipation: a historical review of medical mythopoeia. Gastroenterology 1977;72:957-61. DOI
  6. Saunders D, Sillery J, Chapman R. Effect of calcium carbonate and aluminum hydroxide on human intestinal function. Dig Dis Sci 1988;33:409-13. PubMed
  7. Friedman PA, Bushinsky DA. Diuretic effects on calcium metabolism. Semin Nephrol 1999;19:551-6.
  8. Koo WK, Walters JC, Esterlitz J, et al. Maternal calcium supplementation and fetal bone mineralization. Obstet Gynecol 1999;94:577-82. DOI
  9. Raman L, Rajalakshmi K, Krishnamachari KAVR, et al. Effect of calcium supplementation to undernourished mothers during pregnancy on the bone density of the neonates. Am J Clin Nutr 1978; 31:466-9. DOI
  10. Murry JJ, Healy MD. Drug-mineral interactions: a new responsibility for the hospital dietician. J Am Diet Assoc 1991;91:66-73.
  11. Chan JM, Giovannucci E, Andersson SO, et al. Dairy products, calcium, phosphorous, vitamin D, and risk of prostate cancer. Cancer Causes Control 1998;9:559-66.
  12. Butner LE, Fulco PP, Feldman G, et al. Calcium carbonate-induced hypothyroidism. Ann Intern Med 2000:132:595. PubMed
  13. Schneyer CR. Calcium carbonate and reduction of levothyroxine efficacy. JAMA 1998;279:750. PubMed
  14. Moser LR, Smythe MA, Tisdale JE. The use of calcium salts in the prevention and management of verapamil-induced hypotension. Ann Pharmacother 2000;34:622-9. PubMed
  15. Singh N, Singh PN, Hershman JM. Effect of calcium carbonate on the absorption of levothyroxine. JAMA 2000;283:2822-5. 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 Calcium and Interferon Alfa-2b Together: Common Questions

Is it safe to take Calcium with Interferon Alfa-2b?
We do not list a known interaction between Calcium and Interferon Alfa-2b. 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.
How was the Calcium and Interferon Alfa-2b combination checked?
Interactions in our licensed database are recorded against drug classes. Interferon Alfa-2b is filed under 2 classifications, and Calcium has documented interactions with 18 drug classes — none of Interferon Alfa-2b's classifications are among them. A medication can belong to classes beyond those recorded in our dataset, so this describes how the check was run rather than guaranteeing safety.
Does Calcium interact with any other medications?
Yes. Calcium has 168 documented drug interactions in our database — Interferon Alfa-2b is simply not one of them. If you take anything else, it is worth checking each one; they are all listed on this page.
Does Interferon Alfa-2b interact with any supplements?
Yes. Interferon Alfa-2b has documented interactions with 57 supplements in our database — Calcium is not one of them. The Interferon Alfa-2b 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

Calcium monograph Uses, safety profile, and every drug interaction in one place Interferon Alfa-2b Injection drug information The full plain-English guide to this medication Interferon Alfa-2b supplement interactions Every supplement checked against Interferon Alfa-2b, 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 62 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Interferon Alfa-2b and Calcium?

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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.