Drug & supplement interaction

Annatto + Alosetron

Alosetron brand name: Lotronex.

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 Annatto and Alosetron 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

Annatto and Alosetron

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 Alosetron and Annatto 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.

Annatto safety at a glance

Annatto overall Use caution Generally recognized as safe as a food coloring, but supplement use is not well studied and it can cause allergies in some people.
Pregnancy Use caution Food amounts are likely fine, but concentrated supplement doses are not well studied, so avoid them unless your doctor approves.
Breastfeeding Use caution Food amounts are likely fine, but there is not enough safety information on supplement doses, so use caution.

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

Still wondering about combining Alosetron and Annatto? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Alosetron

Interactions in our licensed database are recorded against drug classes, not just single drug names. Alosetron is filed under 3 classifications — serotonergic drugs, serotonergic drugs, oral drugs. Annatto has documented interactions with 1 drug class — the most serious being antidiabetes drugs (moderate) — and none of Alosetron’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

Annatto Does Interact With Other Medications

Annatto has 86 moderate known drug interactions in our database — Alosetron isn’t one of them. If you take anything else, check it against the full list below.

Moderate 86 No known interaction 2,744 (incl. Alosetron)
Taking anything else?

Check Another of Your Medications Against Annatto

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

What to actually watch for

No Interaction Found — But Data Suggests Annatto and Alosetron 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

    Annatto

    “When used as a food coloring, annatto causes rare cases of allergic reactions in children and adults. Reactions have occurred after consumption of cereal, cheese, ice cream, and other foods containing annatto food coloring, and use of cosmetics containing annatto. Symptoms include urticaria, angioedema, severe hypotension, and anaphylaxis (31619,31621,95157.109549).”

    Annatto · Natural Medicines adverse-effect record, reported in hypotension.

    2 sources cited
    1. 109549. Sadowska B, Sztormowska M, Chelminska M. Annatto hypersensitivity after oral ingestion confirmed by placebo-controlled oral challenge. Ann Allergy Asthma Immunol. 2021 Oct;127(4):510-511. PubMed
    2. 95157. Raddatz-Mota D, Pérez-Flores LJ, Carrari F, et al. Achiote (Bixa orellana L.): a natural source of pigment and vitamin E. J Food Sci Technol 2017;54(6):1729-1741. PubMed

    Alosetron

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

  • Bloating or gas / Stomach pain / Diarrhea Additional detail

    Annatto

    “Orally, annatto leaf powder has been reported to cause constipation. Annatto food coloring has been associated with an increase in symptoms of irritable bowel syndrome (IBS) in one case report. A woman with frequent symptoms of diarrhea, bloating, and abdominal pain experienced an improvement in all symptoms upon elimination of annatto-containing products;”

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

    2 sources cited
    1. 31612. Zegarra, L., Vaisberg, A., Loza, C., Aguirre, R. L., Campos, M., Fernandez, I., Talla, O., and Villegas, L. Double-blind randomized placebo-controlled study of Bixa orellana in patients with lower urinary tract symptoms associated to benign prostatic hyp
    2. 95142. Stein HL. Annatto and IBS. J Clin Gastroenterol 2009;43(10):1014-5.

    Alosetron

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

  • Constipation Additional detail

    Annatto

    “Orally, annatto leaf seems to be well tolerated. Rarely, annatto has been reported to cause constipation. When used as a coloring agent, annatto has been reported to cause allergic reactions, including anaphylaxis.”

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

    5 sources cited
    1. 31612. Zegarra, L., Vaisberg, A., Loza, C., Aguirre, R. L., Campos, M., Fernandez, I., Talla, O., and Villegas, L. Double-blind randomized placebo-controlled study of Bixa orellana in patients with lower urinary tract symptoms associated to benign prostatic hyp
    2. 31619. Ebo, D. G., Ingelbrecht, S., Bridts, C. H., and Stevens, W. J. Allergy for cheese: evidence for an IgE-mediated reaction from the natural dye annatto. Allergy 2009;64(10):1558-1560. PubMed
    3. 31621. Nish, W. A., Whisman, B. A., Goetz, D. W., and Ramirez, D. A. Anaphylaxis to annatto dye: a case report. Ann.Allergy 1991;66(2):129-131.
    4. 95158. Koc E, Arca E, Surucu B, Kurumlu Z. An open, randomized, controlled, comparative study of the combined effect of intralesional triamcinolone acetonide and onion extract gel and intralesional triamcinolone acetonide alone in the treatment of hypertrophic s
    5. 95157. Raddatz-Mota D, Pérez-Flores LJ, Carrari F, et al. Achiote (Bixa orellana L.): a natural source of pigment and vitamin E. J Food Sci Technol 2017;54(6):1729-1741. PubMed

    Alosetron

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

Reported for Annatto but not commonly for Alosetron: an allergic reaction, low blood pressure and a severe allergic reaction.

Effects for Alosetron come from the ADVERSE REACTIONS section of its FDA label; effects for Annatto 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.

From our Q&A

Questions About Annatto or Alosetron

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

This page covers Annatto only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Alosetron page lists 38 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Lithium (major), 5-htp (moderate), Acetyl-l-carnitine (moderate) and Ayahuasca (moderate).

By severity: 2 major · 25 moderate · 11 minor.

From our pharmacist’s overview on the Alosetron page

“Alosetron (Lotronex) treats severe diarrhea-predominant IBS by acting on serotonin receptors in the gut, and that is where most of its 38 supplement interactions come from. Twenty of the ingredients, 5-HTP among them, raise serotonin on their own, and stacking them on a serotonin-acting drug is a combination I want you to treat with re…”

Reviewed by 2 · Jul 18, 2026

Open the Alosetron interaction page

One more smart check

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

We hold 304 real supplement products containing Annatto, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Annatto. Even though Annatto itself has no known interaction with Alosetron, 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 Annatto and Alosetron 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 Annatto
Top half

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

29 days ago today
Medication Alosetron
Steady interest

#1,546 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 Annatto reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Annatto and Alosetron 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 Annatto

What is Annatto?

Annatto
  • Natural food and cosmetic coloring
  • Source of antioxidants
  • Antimicrobial/anti-infective (traditional use)
  • Athletic performance and muscle soreness
  • Skin and bad-breath remedies (traditional use)

Annatto is a plant-based coloring made from the seeds of the achiote tree and is widely used as a safe food dye. While it has a long history in traditional medicine and contains antioxidant compounds, there is little high-quality human research supporting its use as a supplement. It can trigger allergic reactions in some people, so use caution and talk with your pharmacist or doctor.

Bixa orellana · Bixaceae · Seeds (and the colored coating around them); leaves are sometimes used · Food coloring, powder, seed extract, capsules, oil-based extracts

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

Annatto: dosing

There is no established standard dose for annatto as a supplement. The amounts used to color foods are very small, and research has not defined a safe or effective dose for health purposes.If you use an annatto supplement, follow the directions on the product label and do not exceed the recommended amount.

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

Read the full Annatto monograph & all interactions
Medication

About Alosetron

What Is Alosetron Used For?

Brand name: Lotronex

Alosetron tablets — available as Alosetron, Alosetron Hydrochloride, and Lotronex — are approved only for women with severe diarrhea-predominant irritable bowel syndrome (IBS) whose symptoms have lasted 6 months or longer and who have not gotten adequate relief from conventional therapy. Other causes of GI symptoms must be ruled out first.

To qualify as severe, diarrhea-predominant IBS must include diarrhea plus at least one of the following: frequent and severe abdominal pain or discomfort, frequent bowel urgency or fecal incontinence (accidental stool leakage), or significant disruption to daily activities. Clinical studies have not confirmed the same benefit in men.

See full Alosetron drug information
Keep checking

Other Drugs & Annatto

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

0Major
86Moderate
0Minor
2,743No known interaction
86 Moderate 2,743 No interaction
Moderate

86 interactions

Showing 60 of 86 moderate interactions — see all 86 on the Annatto page.

No interaction 2,743 drugs checked — show the list

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

Showing the 60 most looked-up of 2,743 medications checked with no known interaction — see the full Annatto list.

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

Annatto References

The 15 references that drive our Annatto 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. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  2. Fernandes, A. C., Almeida, C. A., Albano, F., Laranja, G. A., Felzenszwalb, I., Lage, C. L., de Sa, C. C., Moura, A. S., and Kovary, K. Norbixin ingestion did not induce any detectable DNA breakage in liver and kidney but caused a considerable impairment
  3. Russell, K. R., Morrison, E. Y., and Ragoobirsingh, D. The effect of annatto on insulin binding properties in the dog. Phytother Res 2005;19(5):433-436. PubMed
  4. Morrison, E. Y., Thompson, H., Pascoe, K., West, M., and Fletcher, C. Extraction of an hyperglycaemic principle from the annatto (Bixa orellana), a medicinal plant in the West Indies. Trop.Geogr.Med 1991;43(1-2):184-188.
  5. Zegarra, L., Vaisberg, A., Loza, C., Aguirre, R. L., Campos, M., Fernandez, I., Talla, O., and Villegas, L. Double-blind randomized placebo-controlled study of Bixa orellana in patients with lower urinary tract symptoms associated to benign prostatic hyp
  6. Russell, K. R., Omoruyi, F. O., Pascoe, K. O., and Morrison, E. Y. Hypoglycaemic activity of Bixa orellana extract in the dog. Methods Find.Exp.Clin.Pharmacol. 2008;30(4):301-305.
  7. Ebo, D. G., Ingelbrecht, S., Bridts, C. H., and Stevens, W. J. Allergy for cheese: evidence for an IgE-mediated reaction from the natural dye annatto. Allergy 2009;64(10):1558-1560. PubMed
  8. Nish, W. A., Whisman, B. A., Goetz, D. W., and Ramirez, D. A. Anaphylaxis to annatto dye: a case report. Ann.Allergy 1991;66(2):129-131.
  9. Stein HL. Annatto and IBS. J Clin Gastroenterol 2009;43(10):1014-5.
  10. Raddatz-Mota D, Pérez-Flores LJ, Carrari F, et al. Achiote (Bixa orellana L.): a natural source of pigment and vitamin E. J Food Sci Technol 2017;54(6):1729-1741. PubMed
  11. Koc E, Arca E, Surucu B, Kurumlu Z. An open, randomized, controlled, comparative study of the combined effect of intralesional triamcinolone acetonide and onion extract gel and intralesional triamcinolone acetonide alone in the treatment of hypertrophic s
  12. Gonçalves MLL, da Mota ACC, Deana AM, et al. Antimicrobial photodynamic therapy with Bixa orellana extract and blue LED in the reduction of halitosis-A randomized, controlled clinical trial. Photodiagnosis Photodyn Ther. 2020 Jun;30:101751. PubMed
  13. Dominguez-Balmaseda D, Diez-Vega I, Larrosa M, et al. Effect of a blend of Zingiber officinale Roscoe and Bixa orellana L. herbal supplement on the recovery of delayed-onset muscle soreness induced by unaccustomed eccentric resistance training: A randomiz
  14. González-Gross M, Quesada-González C, Rueda J, et al. Analysis of effectiveness of a supplement combining Harpagophytum procumbens, Zingiber officinale and Bixa orellana in healthy recreational runners with self-reported knee pain: a pilot, randomized, tr
  15. Sadowska B, Sztormowska M, Chelminska M. Annatto hypersensitivity after oral ingestion confirmed by placebo-controlled oral challenge. Ann Allergy Asthma Immunol. 2021 Oct;127(4):510-511. 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 Annatto and Alosetron Together: Common Questions

Is it safe to take Annatto with Alosetron?
We do not list a known interaction between Annatto and Alosetron. 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 Annatto and Alosetron 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.
How was the Annatto and Alosetron combination checked?
Interactions in our licensed database are recorded against drug classes. Alosetron is filed under 3 classifications, and Annatto has documented interactions with 1 drug class — none of Alosetron'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 Annatto interact with any other medications?
Yes. Annatto has 86 documented drug interactions in our database — Alosetron 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 Alosetron interact with any supplements?
Yes. Alosetron has documented interactions with 38 supplements in our database — Annatto is not one of them. The Alosetron 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

Annatto monograph Uses, safety profile, and every drug interaction in one place Alosetron drug information The full plain-English guide to this medication Alosetron supplement interactions Every supplement checked against Alosetron, 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 15 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Alosetron and Annatto?

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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.