Drug & supplement interaction

Canthaxanthin + Diltiazem

Diltiazem brand names: Cardizem, Cardizem SR, Diltiaz SR, Cardizem CD, Tiazac, and others.

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 Canthaxanthin and Diltiazem 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

Canthaxanthin and Diltiazem

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 Diltiazem and Canthaxanthin 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 Canthaxanthin at all — not against Diltiazem, 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.

Canthaxanthin safety at a glance

Canthaxanthin overall Use caution Generally fine in small food-coloring amounts, but high-dose supplements have been linked to eye and other problems.
Pregnancy Possibly Unsafe When consumed in doses to treat and reduce photosensitivities due to reported retinal changes with use; avoid using. Read the full pregnancy detail
Breastfeeding Possibly Unsafe When consumed in doses to treat and reduce photosensitivities due to reported retinal changes with use; avoid using. 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 Diltiazem and Canthaxanthin? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
What to actually watch for

No Interaction Found — But Data Suggests Canthaxanthin and Diltiazem 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.

  • Hives Worth acting on Additional detail

    Canthaxanthin

    “Orally, large amounts of canthaxanthin can cause orange-brown coloration of the skin, brick-red coloration of stools, orange discoloration of plasma, discolored body secretions, diarrhea, nausea, stomach cramps, dry and itchy skin, urticaria, welts, gold and yellow crystalline deposits around the macula of the retina, and hepatitis.”

    Canthaxanthin · Natural Medicines adverse-effect record, reported in anemia.

    6 sources cited
    1. 5632. Lober CW. Canthaxanthin- the "tanning" pill. J Am Acad Dermatol 1985;13:660. PubMed
    2. 5631. Jackson R. Quick suntan pills in Canada. J Am Acad Dermatol 1981;4:233. PubMed
    3. 5634. Rock GA, Decary F, Cole RS. Orange plasma from tanning capsules. Lancet 1981;1:1419-20. PubMed
    4. 5637. Herbert V. Canthaxanthin toxicity. Am J Clin Nutr 1991;53:573-4. DOI
    5. 5635. Bluhm R, Branch R, Johnston P, Stein R. Aplastic anemia associated with canthaxanthin ingested for 'tanning' purposes. JAMA 1990;264:1141-2. DOI
    6. 5636. Harnois C, Samson J, Malenfant M, Rousseau A. Canthaxanthin retinopathy. Anatomic and funtional reversibility. Arch Ophthalmol 1989;107:538-40. DOI

    “Orally, large amounts of canthaxanthin can cause orange-brown coloration of the skin. Large amounts of canthaxanthin orally can cause dry and itchy skin, urticaria, and welts.”

    Canthaxanthin · Natural Medicines adverse-effect record, reported in urticaria.

    6 sources cited
    1. 5632. Lober CW. Canthaxanthin- the "tanning" pill. J Am Acad Dermatol 1985;13:660. PubMed
    2. 39713. Gupta, A. K., Haberman, H. F., Pawlowski, D., Shulman, G., and Menon, I. A. Canthaxanthin. Int.J.Dermatol. 1985;24(8):528-532.
    3. 39720. Macdonald, K., Holti, G., and Marks, J. Is there a place for beta-carotene/canthaxanthin in photochemotherapy for psoriasis? Dermatologica 1984;169(1):41-46.
    4. 34657. Suhonen, R. and Plosila, M. The effect of beta-carotene in combination with canthaxanthin, Ro 8-8427 (Phenoro), in treatment of polymorphous light eruptions. Dermatologica 1981;163(2):172-176. PubMed
    5. 5634. Rock GA, Decary F, Cole RS. Orange plasma from tanning capsules. Lancet 1981;1:1419-20. PubMed
    6. 5637. Herbert V. Canthaxanthin toxicity. Am J Clin Nutr 1991;53:573-4. DOI

    Diltiazem

    Listed in the ADVERSE REACTIONS section of the FDA label for Diltiazem. Read the label on DailyMed ›

  • Itching Additional detail

    Canthaxanthin

    Recorded for Canthaxanthin in the same Natural Medicines adverse-effect record shown under Hives above.

    Diltiazem

    Listed in the ADVERSE REACTIONS section of the FDA label for Diltiazem. Read the label on DailyMed ›

  • Diarrhea / Nausea reported in 7.1% of FDA reports for Diltiazem Additional detail

    Canthaxanthin

    “Orally, canthaxanthin can cause orange or brick-red discoloration of stools. Large amounts of canthaxanthin orally can cause diarrhea, nausea, and stomach cramps.”

    Canthaxanthin · Natural Medicines adverse-effect record, reported in diarrhea.

    4 sources cited
    1. 5631. Jackson R. Quick suntan pills in Canada. J Am Acad Dermatol 1981;4:233. PubMed
    2. 39713. Gupta, A. K., Haberman, H. F., Pawlowski, D., Shulman, G., and Menon, I. A. Canthaxanthin. Int.J.Dermatol. 1985;24(8):528-532.
    3. 34657. Suhonen, R. and Plosila, M. The effect of beta-carotene in combination with canthaxanthin, Ro 8-8427 (Phenoro), in treatment of polymorphous light eruptions. Dermatologica 1981;163(2):172-176. PubMed
    4. 5634. Rock GA, Decary F, Cole RS. Orange plasma from tanning capsules. Lancet 1981;1:1419-20. PubMed

    Diltiazem

    Listed in the ADVERSE REACTIONS section of the FDA label for Diltiazem, and in voluntary FDA adverse-event reports. Read the label on DailyMed ›

Reported for Canthaxanthin but not commonly for Diltiazem: stomach pain, liver problems and anemia.

Effects for Diltiazem come from the ADVERSE REACTIONS section of its FDA label; effects for Canthaxanthin come from the Natural Medicines adverse-effect record, quoted above. Where a percentage is shown, it is the share of 34,400 voluntary FDA FAERS reports for Diltiazem that mention that effect — a reporting proportion, not an incidence rate and not evidence the drug caused it. Wording is matched across sources by our own clinical vocabulary, so treat this as a prompt to pay attention, not a diagnosis.

Special populations

Canthaxanthin in Pregnancy & Breastfeeding

Pregnancy And Lactation Possibly Unsafe

When consumed in doses to treat and reduce photosensitivities due to reported retinal changes with use; avoid using.

Pregnancy And Lactation Likely Unsafe

When used orally in large amounts for artificial tanning purposes due to reported retinal changes with use; avoid using.

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 Canthaxanthin or Diltiazem

These are real questions from readers, answered by the pharmacists at HelloPharmacist — written by a person, not generated from a database. Each one covers Canthaxanthin or Diltiazem, 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 Diltiazem

This page covers Canthaxanthin only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Diltiazem page lists 260 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Hellebore (major), American Mistletoe (major), Coleus (major) and Grapefruit (major).

By severity: 7 major · 214 moderate · 39 minor.

From our pharmacist’s overview on the Diltiazem page

“Someone on diltiazem (Cardizem, Tiazac) is usually managing blood pressure, angina, or a fast heart rhythm, so this list deserves genuine care. Seven of the 260 ingredients on file carry a major rating, and two of those are things people actually buy: grapefruit, which blocks the enzyme that clears diltiazem and can push its blood leve…”

Reviewed by 2 · Jul 18, 2026

Open the Diltiazem interaction page

One more smart check

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

We hold 1 real supplement products containing Canthaxanthin, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Canthaxanthin. Even though Canthaxanthin itself has no known interaction with Diltiazem, 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 Canthaxanthin and Diltiazem 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 Canthaxanthin
Steady interest

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

29 days ago today
Medication Diltiazem
Top 10%

#279 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 Canthaxanthin reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Canthaxanthin and Diltiazem 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 Canthaxanthin

What is Canthaxanthin?

  • Skin coloring or 'tanning pills'
  • Food and feed coloring (e.g., to color farmed fish/poultry)
  • Antioxidant supplement
  • Erythropoietic protoporphyria (light sensitivity, historical/medical use)

Canthaxanthin is a reddish-orange carotenoid pigment used mainly as a coloring agent and in 'tanning pills.' There is little good evidence it provides health benefits, and high doses have been linked to a serious eye problem called canthaxanthin retinopathy, so the tanning-pill use is widely discouraged.

Carotenoid pigment (synthetic or from sources like the mushroom Cantharellus cinnabarinus, certain algae, and crustaceans) · Oral tablets and capsules, often marketed as 'tanning pills'; also used as a food coloring additive

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

Canthaxanthin: dosing

There is no established, recommended supplement dose of canthaxanthin for any health condition, and the high doses once used for skin coloring are not considered safe. Given the known risks at high doses, most people are better off avoiding supplemental canthaxanthin entirely.

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

Read the full Canthaxanthin monograph & all interactions
Medication

About Diltiazem

What Is Diltiazem Used For?

Brand names: Cardizem, Cardizem SR, Diltiaz SR, Cardizem CD, Tiazac, Diltiaz XT, Diltiaz CD, Dilacor, Diltiaz, Cardizem LA, Dilacor XR, Cartia XT, Tiamate, Adizem-SR, Adizem-XL, Angitil SR, Angitil XL, Calcicard CR, Dilcardia SR, Dilzem SR, Dilzem XL, Slozem, Tildiem LA, Tildiem Retard, Viazem XL, Zemtard 120XL, Zemtard 180XL, Zemtard 240XL, Zemtard 300XL

Oral extended-release forms of diltiazem — including Matzim LA, Cardizem LA, Cartia, Cartia XT, Tiadylt ER, and various generic capsules and tablets — are used to treat high blood pressure (hypertension) and chronic stable angina (chest pain brought on by activity). Some capsule formulations, including Cartia, Cartia XT, and certain generics, are also approved for angina due to coronary artery spasm (sudden chest pain caused by a sudden tightening of a coronary artery).

Injectable forms of diltiazem are used in hospital settings to temporarily slow a dangerously fast heart rate in atrial fibrillation or atrial flutter (rapid, irregular heart rhythms), and to restore a normal heart rhythm in paroxysmal supraventricular tachycardia (PSVT) — sudden episodes of a very fast but regular heartbeat originating above the heart's lower chambers.

Most-Reported Side Effects for Diltiazem

From FAERS, the FDA’s public side-effect reporting system (34,400 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dyspnea 3,309 reports
Fatigue 2,733 reports
Nausea 2,454 reports
Dizziness 2,174 reports
Diarrhea 2,113 reports
See full Diltiazem drug information
Keep checking

Other Drugs & Canthaxanthin

Browse every other medication we’ve checked against Canthaxanthin — 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 Canthaxanthin 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 Canthaxanthin list.

See the full Canthaxanthin interactions page
See every supplement checked against Diltiazem, ranked by severity
Evidence & sources

Canthaxanthin References

The 21 references that drive our Canthaxanthin 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. Mathews-Roth MM. Carotenoids in erythropoietic protoporphyria and other photosensitivity diseases. Ann N Y Acad Sci, 1993; 691:127-38. PubMed
  2. Jackson R. Quick suntan pills in Canada. J Am Acad Dermatol 1981;4:233. PubMed
  3. Lober CW. Canthaxanthin- the "tanning" pill. J Am Acad Dermatol 1985;13:660. PubMed
  4. Rock GA, Decary F, Cole RS. Orange plasma from tanning capsules. Lancet 1981;1:1419-20. PubMed
  5. Bluhm R, Branch R, Johnston P, Stein R. Aplastic anemia associated with canthaxanthin ingested for 'tanning' purposes. JAMA 1990;264:1141-2. DOI
  6. Harnois C, Samson J, Malenfant M, Rousseau A. Canthaxanthin retinopathy. Anatomic and funtional reversibility. Arch Ophthalmol 1989;107:538-40. DOI
  7. Herbert V. Canthaxanthin toxicity. Am J Clin Nutr 1991;53:573-4. DOI
  8. White GL Jr, Beesley R, Thiese SM, Murdock RT. Retinal crystals and oral tanning agents. Am Fam Physician 1988;37:125-6.
  9. Chang TS, Aylward W, Clarkson JG, Gass JD. Asymmetric canthaxanthin retinopathy. Am J Ophthalmol 1995;119:801-2. PubMed
  10. Leyon H, Ros AM, Nyberg S, Algvere P. Reversibility of canthaxanthin deposits within the retina. Acta Ophthalmol (Copenh) 1990;68:607-11. PubMed
  11. Espaillat A, Aiello LP, Arrigg PG, et al. Canthaxanthine retinopathy. Arch Ophthalmol 1999;117:412-3.. PubMed
  12. Anon. Porphyria information for patients and their families. University of Cape Town / Medical Research Council - Liver Research Center 2000. Available at: http://web.uct.ac.za/depts/porphyria/
  13. Thomsen, K., Schmidt, H., and Fischer, A. Beta-carotene in erythropoietic protoporphyria: 5 years' experience. Dermatologica 1979;159(1):82-86. PubMed
  14. Haeger-Aronsen, B., Krook, G., and Abdulla, M. Oral carotenoids for photohypersensitivity in patients with erythrohepatic protoporphyria, polymorphous light eruptions and lupus erythematodes discoides. Int.J.Dermatol. 1979;18(1):73-82. PubMed
  15. Suhonen, R. and Plosila, M. The effect of beta-carotene in combination with canthaxanthin, Ro 8-8427 (Phenoro), in treatment of polymorphous light eruptions. Dermatologica 1981;163(2):172-176. 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 Canthaxanthin and Diltiazem Together: Common Questions

Is it safe to take Canthaxanthin with Diltiazem?
We do not list a known interaction between Canthaxanthin and Diltiazem. 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 Canthaxanthin and Diltiazem 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 Diltiazem interact with any supplements?
Yes. Diltiazem has documented interactions with 260 supplements in our database — Canthaxanthin is not one of them. The Diltiazem 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

Canthaxanthin monograph Uses, safety profile, and every drug interaction in one place Diltiazem drug information The full plain-English guide to this medication Diltiazem supplement interactions Every supplement checked against Diltiazem, 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 21 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Diltiazem and Canthaxanthin?

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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.