Drug & supplement interaction

Cinchona + Silodosin

Silodosin brand name: Rapaflo.

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 Cinchona and Silodosin 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 label for Silodosin states a food rule worth keeping to, and 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

Cinchona and Silodosin

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 Silodosin and Cinchona 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.

Cinchona safety at a glance

Cinchona overall Use caution Contains quinine, which can cause serious side effects, and the bark is not dose-controlled.
Pregnancy Likely Unsafe When used orally. Cinchona is reported to have uterine stimulant and abortifacient activity, and to be fetotoxic and teratogenic, causing visual and auditory de... Read the full pregnancy detail
Breastfeeding Possibly Unsafe When used orally. The cinchona alkaloids quinine and quinidine are reported to be excreted in breast milk and may be toxic to infants. 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 Silodosin and Cinchona? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Silodosin

Interactions in our licensed database are recorded against drug classes, not just single drug names. Silodosin is filed under 4 classifications — including alpha-adrenergic antagonists, p-glycoprotein substrates, cytochrome p450 3a4 (cyp3a4) substrates. Cinchona has documented interactions with 11 drug classes — the most serious being quinidine (major), quinine (major) and antacids (moderate) — and none of Silodosin’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

Cinchona Does Interact With Other Medications

Cinchona has 3 major, 473 moderate, 16 minor known drug interactions in our database — Silodosin isn’t one of them. If you take anything else, check it against the full list below.

Major 3 Moderate 473 Minor 16 No known interaction 2,338 (incl. Silodosin)
Taking anything else?

Check Another of Your Medications Against Cinchona

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

What to actually watch for

No Interaction Found — But Data Suggests Cinchona and Silodosin 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. 2 of them are worth acting on rather than waiting out — marked below.

  • Hives Worth acting on Additional detail

    Cinchona

    “Information on the adverse effects of cinchona is limited. Orally, prolonged use of high doses of cinchona can cause severe adverse effects. Topically, a thorough evaluation of safety outcomes has not been conducted.

    Most Common Adverse Effects:

    Orally: Diarrhea, nausea, ringing ears, vomiting.

    Topically: Contact dermatitis, urticaria.

    Serious Adverse Effects (Rare):

    Orally: Arrhythmias, cinchonism syndrome, hemolyti…”

    Cinchona · Natural Medicines adverse-effect record, reported in arrhythmia.

    Silodosin

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

  • Bleeding or bruising Worth acting on Additional detail

    Cinchona

    “Quinine, which is present in cinchona, has been associated with serious, sometimes fatal, hematological disorders including thrombocytopenia, thrombotic thrombocytopenic purpura (TTP), and hemolytic uremic syndrome (hemolytic anemia, acute renal failure, and thrombocytopenia). Initial symptoms may include bleeding from the gums, nose or gastrointestinal tract, easy bruising, and petechiae.”

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

    3 sources cited
    1. 93232. US Food and Drug Administration notice: Drug products containing quinine - enforcement action dates. Docket # 2006N-0476. Federal Register 2006 (December 15);71 (241): 75557-60.
    2. 93233. FDA Drug Safety Communication: New risk management plan and patient medication guide for Qualaquin (quinine sulfate). 07-08-2010. https://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm218202 (accessed 02/18/17).
    3. 505. Hardman JG, Limbird LL, Molinoff PB, eds. Goodman and Gillman's The Pharmacological Basis of Therapeutics, 9th ed. New York, NY: McGraw-Hill, 1996.

    Silodosin

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

  • Low blood pressure / Stomach pain / Dizziness / Headache Additional detail

    Cinchona

    “Orally, prolonged use of high doses of cinchona or its alkaloids, or a single dose of 3 grams or more of the alkaloid quinine are associated with a toxicity syndrome known as cinchonism. Symptoms include headache, dizziness, nausea and vomiting, diarrhea, hemolysis, hypotension, cardiac arrhythmias, tinnitus, deafness, vision changes, blindness, abdominal pain, delirium, convulsions, paralysis, and collapse (6,12,19,…”

    Cinchona · Natural Medicines adverse-effect record, reported in arrhythmia.

    6 sources cited
    1. 6. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
    2. 12. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
    3. 19. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
    4. 505. Hardman JG, Limbird LL, Molinoff PB, eds. Goodman and Gillman's The Pharmacological Basis of Therapeutics, 9th ed. New York, NY: McGraw-Hill, 1996.
    5. 93232. US Food and Drug Administration notice: Drug products containing quinine - enforcement action dates. Docket # 2006N-0476. Federal Register 2006 (December 15);71 (241): 75557-60.
    6. 18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.

    Silodosin

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

  • Itching / Swelling Additional detail

    Cinchona

    “Topical use of cinchona bark extracts and occupational exposure to cinchona bark dust can cause contact dermatitis and other urticarial reactions (11,93234). A 31-year old man developed itching, erythema, and edema of the face and upper chest after occupational exposure to dust from cinchona bark.”

    Cinchona · Natural Medicines adverse-effect record, reported in dermatitis.

    2 sources cited
    1. 11. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
    2. 93234. Dooms-Goossens A, Deveylder H, Duron C, et al. Airborne contact urticaria due to cinchona. Contact Dermatitis 1986;15(4):258. PubMed

    Silodosin

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

  • Diarrhea Additional detail

    Cinchona

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

    Silodosin

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

  • A skin rash Additional detail

    Cinchona

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

    Silodosin

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

Reported for Cinchona but not commonly for Silodosin: an irregular heartbeat, a low platelet count, blurred vision and kidney problems.

Effects for Silodosin come from the ADVERSE REACTIONS section of its FDA label; effects for Cinchona 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

Cinchona in Pregnancy & Breastfeeding

Pregnancy Likely Unsafe

When used orally. Cinchona is reported to have uterine stimulant and abortifacient activity, and to be fetotoxic and teratogenic, causing visual and auditory defects. Avoid using.

Lactation Possibly Unsafe

When used orally. The cinchona alkaloids quinine and quinidine are reported to be excreted in breast milk and may be toxic to infants.

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

How to take them

Some Silodosin Products Have a Food Rule — Cinchona Should Not Break It

At least one FDA label for a product containing Silodosin says to take it with food. If you take Cinchona on an empty stomach out of habit, keep them separate — and take Silodosin with a meal where the label says to.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Silodosin products can carry different directions, and extended-release forms often differ from immediate-release ones. The label we read is quoted below — check the directions on your own box or bottle, or ask your pharmacist, for how to take the exact product you were given.

2 DOSAGE AND ADMINISTRATION 8 mg capsules taken orally once daily with a meal.

From the Dosage and Administration section of the FDA label we read for Silodosin — where that label names a specific product, the instruction is that product's. Read the label on DailyMed ›

A food rule is not an interaction — it is about how much of the medicine you absorb. The directions that came with your own product, and your pharmacist, outrank anything on this page.

From our Q&A

Questions About Cinchona or Silodosin

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

This page covers Cinchona only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Silodosin page lists 145 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Grapefruit (major), St. John's Wort (major), Acacia Rigidula (moderate) and Adrafinil (moderate).

By severity: 3 major · 104 moderate · 38 minor.

From our pharmacist’s overview on the Silodosin page

“Grapefruit is the first risk I'd flag for anyone taking silodosin (Rapaflo) for an enlarged prostate. It blocks CYP3A4, the enzyme that clears silodosin, so blood levels rise, and higher levels mean more dizziness, lightheadedness, and fainting when standing.”

Reviewed by 2 · Jul 18, 2026

Open the Silodosin interaction page

One more smart check

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

We hold 12 real supplement products containing Cinchona, each one broken down to its full ingredient list — and combination products often carry several ingredients besides Cinchona. Even though Cinchona itself has no known interaction with Silodosin, 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 Cinchona and Silodosin 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 Cinchona
Steady interest

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

29 days ago today
Medication Silodosin
Steady interest

#1,715 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 Cinchona reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 20, 2026. The Cinchona and Silodosin records this page draws on were last updated July 11, 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 Cinchona

What is Cinchona?

Cinchona
  • Malaria (historical/traditional)
  • Fever
  • Leg cramps and restless legs
  • Digestive upset and loss of appetite
  • Bitter tonic

Cinchona bark is the natural source of quinine and has been used for centuries to treat malaria and fever, but the bark itself is not standardized and can be unpredictable and risky. Modern medicine uses purified, dose-controlled quinine instead, and the supplement form carries real dangers, including serious heart and blood problems. Talk to a pharmacist or doctor before using it, and avoid it during pregnancy.

Cinchona officinalis · Rubiaceae · Bark · Dried bark, tinctures, liquid extracts, capsules, teas, and as a bitter flavoring in tonic water

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

Cinchona: dosing

There is no well-established safe dose for cinchona bark as a supplement. The amount of quinine and other alkaloids can vary a lot from product to product, which makes safe dosing difficult.If you are considering a cinchona product, follow the directions on the label and do not exceed them.

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

Read the full Cinchona monograph & all interactions
Medication

About Silodosin

What Is Silodosin Used For?

Brand name: Rapaflo

Silodosin capsules are approved to treat the signs and symptoms of benign prostatic hyperplasia (BPH) — the non-cancerous enlargement of the prostate that can make urination difficult, weak, or frequent. It helps ease those urinary symptoms so urine can flow more freely.

It is important to know that silodosin is not approved for treating high blood pressure, even though it affects certain receptors that can influence blood pressure.

Most-Reported Side Effects for Silodosin

From FAERS, the FDA’s public side-effect reporting system (0 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Diarrhea 156 reports
Fatigue 149 reports
Dizziness 141 reports
Acute kidney injury 139 reports
Anemia 126 reports
See full Silodosin drug information
Keep checking

Other Drugs & Cinchona

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

3Major
473Moderate
16Minor
2,337No known interaction
3 Major 473 Moderate 16 Minor 2,337 No interaction
Major

3 interactions

Moderate

473 interactions

Showing 60 of 473 moderate interactions — see all 473 on the Cinchona page.

Minor

16 interactions

No interaction 2,337 drugs checked — show the list

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

Showing the 60 most looked-up of 2,337 medications checked with no known interaction — see the full Cinchona list.

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

Cinchona References

The 15 references that drive our Cinchona 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. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  2. Wichtl MW. Herbal Drugs and Phytopharmaceuticals. Ed. N.M. Bisset. Stuttgart: Medpharm GmbH Scientific Publishers, 1994.
  3. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  4. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  5. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  6. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  7. Holt GA. Food & Possible Interactions with Drugs: Revised and Expanded Ed. Chicago, IL: Precept Press, 1998.
  8. Hardman JG, Limbird LL, Molinoff PB, eds. Goodman and Gillman's The Pharmacological Basis of Therapeutics, 9th ed. New York, NY: McGraw-Hill, 1996.
  9. Hansten PD, Horn JR. Drug Interactions Analysis and Management. Vancouver, WA: Applied Therapeutics Inc., 1997 and updates.
  10. Amabeoku GJ, Chikuni O, Akino C, Mutetwa S. Pharmacokinetic interaction of single doses of quinine and carbamazepine, phenobarbitone and phenytoin in healthy volunteers. East Afr Med J 1993;70:90-3.
  11. Shah BH, Nawaz Z, Virani SS, Ali IQ, Saeed SA, Gilani AH.The inhibitory effect of cinchonine on human platelet aggregation due to blockade of calcium influx. Biochem Pharmacol 1998;56:955-60. PubMed
  12. US Food and Drug Administration notice: Drug products containing quinine - enforcement action dates. Docket # 2006N-0476. Federal Register 2006 (December 15);71 (241): 75557-60.
  13. FDA Drug Safety Communication: New risk management plan and patient medication guide for Qualaquin (quinine sulfate). 07-08-2010. https://www.fda.gov/Drugs/DrugSafety/PostmarketDrugSafetyInformationforPatientsandProviders/ucm218202 (accessed 02/18/17).
  14. Dooms-Goossens A, Deveylder H, Duron C, et al. Airborne contact urticaria due to cinchona. Contact Dermatitis 1986;15(4):258. PubMed
  15. Bramer SL, Suri A. Inhibition of CYP2D6 by quinidine and its effects on the metabolism of cilostazol. Clin Pharmacokinet. 1999;37 Suppl 2:41-51. 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 Cinchona and Silodosin Together: Common Questions

Is it safe to take Cinchona with Silodosin?
We do not list a known interaction between Cinchona and Silodosin. 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 Cinchona and Silodosin have any of the same side effects?
Yes — our sources link each of them separately to 10 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.
Should I take Cinchona and Silodosin at the same time of day?
At least one FDA label for a product containing Silodosin says to take it with food. If you take Cinchona on an empty stomach out of habit, keep them separate and take Silodosin with a meal where the label says to. Food instructions belong to the product rather than the ingredient — two Silodosin products can differ — so check the directions on your own box. This is about absorption, not an interaction.
How was the Cinchona and Silodosin combination checked?
Interactions in our licensed database are recorded against drug classes. Silodosin is filed under 4 classifications, and Cinchona has documented interactions with 11 drug classes — none of Silodosin'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 Cinchona interact with any other medications?
Yes. Cinchona has 492 documented drug interactions in our database — Silodosin 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 Silodosin interact with any supplements?
Yes. Silodosin has documented interactions with 145 supplements in our database — Cinchona is not one of them. The Silodosin 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

Cinchona monograph Uses, safety profile, and every drug interaction in one place Silodosin drug information The full plain-English guide to this medication Silodosin supplement interactions Every supplement checked against Silodosin, 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 Silodosin and Cinchona?

Our pharmacists answer your medication & supplement questions — free.

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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.