Drug & supplement interaction

Fever Bark + Sildenafil

Sildenafil brand name: Revatio.

No Known Interaction
Medically reviewed by · Updated July 2026 · Pair last verified Sep 13, 2026
The bottom line No known interaction

We found no known interaction between Fever Bark and Sildenafil 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

Fever Bark and Sildenafil

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 Sildenafil and Fever Bark 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.

Fever Bark safety at a glance

Fever Bark overall Use caution The bark contains strong alkaloids and is not recommended without professional supervision.
Pregnancy Avoid Not enough safety data and potent alkaloids make it unsafe to use during pregnancy.
Breastfeeding Avoid No reliable safety information exists, so avoid use while breastfeeding.

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

Still wondering about combining Sildenafil and Fever Bark? Ask Dr. Brian Staiger, PharmD, BCPS directly ›
How we checked

Why No Interaction Is Listed for Sildenafil

Interactions in our licensed database are recorded against drug classes, not just single drug names. Sildenafil is filed under 6 classifications — including phosphodiesterase-5 inhibitors, vasodilators, cytochrome p450 2c9 (cyp2c9) substrates. Fever Bark has documented interactions with 9 drug classes — the most serious being anesthesia (major), monoamine oxidase inhibitors (maois) (major) and antihypertensive drugs (moderate) — and none of Sildenafil’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

Fever Bark Does Interact With Other Medications

Fever Bark has 40 major, 674 moderate, 87 minor known drug interactions in our database — Sildenafil isn’t one of them. If you take anything else, check it against the full list below.

Major 40 Moderate 674 Minor 87 No known interaction 2,029 (incl. Sildenafil)
Taking anything else?

Check Another of Your Medications Against Fever Bark

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

What to actually watch for

No Interaction Found — But Data Suggests Fever Bark and Sildenafil 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.

  • A stuffy or runny nose Additional detail

    Fever Bark

    “The yohimbine constituent of fever bark, when taken alone, may cause bronchospasm, tachynpea, cough, and rhinorrhea. The reserpine constituent of fever bark, when taken alone, may cause nasal congestion or bronchospasm (15,94328). It is not known if this occurs with fever bark.”

    Fever Bark · Natural Medicines adverse-effect record, reported in cough.

    5 sources cited
    1. 17465. Kearney T, Tu N, Haller C. Adverse drug events associated with yohimbine-containing products: a retrospective review of the California Poison Control System reported cases. Ann Pharmacother 2010;44:1022-9. PubMed
    2. 86825. Landis, E. and Shore, E. Yohimbine-induced bronchospasm. Chest 1989;96(6):1424. PubMed
    3. 86850. Charney, D. S., Heninger, G. R., and Sternberg, D. E. Assessment of alpha 2 adrenergic autoreceptor function in humans: effects of oral yohimbine. Life Sci 6-7-1982;30(23):2033-2041.
    4. 15. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
    5. 94328. Lobay D. Rauwolfia in the Treatment of Hypertension. Integr Med (Encinitas). 2015 Jun;14(3):40-6.

    Sildenafil

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

  • Muscle pain Additional detail

    Fever Bark

    “The yohimbine constituent of fever bark, when taken alone, causes may cause muscle aches. It is not known if this occurs with fever bark.”

    Fever Bark · Natural Medicines adverse-effect record, reported in fever.

    1 source cited
    1. 86850. Charney, D. S., Heninger, G. R., and Sternberg, D. E. Assessment of alpha 2 adrenergic autoreceptor function in humans: effects of oral yohimbine. Life Sci 6-7-1982;30(23):2033-2041.

    Sildenafil

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

  • Stomach upset Additional detail

    Fever Bark

    “The yohimbine constituent of fever bark, when taken alone, causes salivation, diarrhea, and gastrointestinal distress. The reserpine constituent of fever bark, when taken alone, can cause peptic ulceration (17). It is not known if these effects occur with fever bark.”

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

    6 sources cited
    1. 3970. Jacobsen FM. Fluoxetine-induced sexual dysfunction and an open trial of yohimbine. J Clin Psychiatry 1992;53:119-22.
    2. 17465. Kearney T, Tu N, Haller C. Adverse drug events associated with yohimbine-containing products: a retrospective review of the California Poison Control System reported cases. Ann Pharmacother 2010;44:1022-9. PubMed
    3. 49902. Abebe, W. An overview of herbal supplement utilization with particular emphasis on possible interactions with dental drugs and oral manifestations. J Dent.Hyg. 2003;77(1):37-46.
    4. 86780. Bagheri, H., Schmitt, L., Berlan, M., and Montastruc, J. L. Effect of 3 weeks treatment with yohimbine on salivary secretion in healthy volunteers and in depressed patients treated with tricyclic antidepressants. Br J Clin Pharmacol 1992;34(6):555-558. PubMed
    5. 86781. Bagheri, H., Bompart, G., Girolami, J. P., Montastruc, J. L., and Montastruc, P. Is yohimbine-induced increase in salivary secretion a kinin-dependent mechanism? Fundam.Clin Pharmacol 1992;6(1):17-20. PubMed
    6. 86786. Adeniyi, A. A., Brindley, G. S., Pryor, J. P., and Ralph, D. J. Yohimbine in the treatment of orgasmic dysfunction. Asian J Androl 2007;9(3):403-407. PubMed

    Sildenafil

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

  • Dizziness / Headache Additional detail

    Fever Bark

    “The yohimbine constituent of fever bark, when taken alone in high doses, causes general central nervous system and autonomic excitation, tremulousness, head twitching, seizure threshold changes, dizziness, vertigo, and headache. It is not known if this occurs with fever bark.”

    Fever Bark · Natural Medicines adverse-effect record, reported in cluster headache.

    6 sources cited
    1. 3312. Teloken C, Rhoden EL, Sogari P, et al. Therapeutic effects of high dose yohimbine hydrochloride on organic erectile dysfunction. J Urol 1998;159:122-4. PubMed
    2. 3971. Hollander E, McCarley A. Yohimbine treatment of sexual side effects induced by serotonin reuptake blockers. J Clin Psychiatry 1992;53:207-9.
    3. 86774. Cameron, O. G., Zubieta, J. K., Grunhaus, L., and Minoshima, S. Effects of yohimbine on cerebral blood flow, symptoms, and physiological functions in humans. Psychosom.Med 2000;62(4):549-559. PubMed
    4. 86779. Bowes, M. P., Peters, R. H., Kernan, W. J., Jr., and Hopper, D. L. Effects of yohimbine and idazoxan on motor behaviors in male rats. Pharmacol.Biochem.Behav. 1992;41(4):707-713.
    5. 86786. Adeniyi, A. A., Brindley, G. S., Pryor, J. P., and Ralph, D. J. Yohimbine in the treatment of orgasmic dysfunction. Asian J Androl 2007;9(3):403-407. PubMed
    6. 86804. Myers, A. and Barrueto, F., Jr. Refractory priapism associated with ingestion of yohimbe extract. J Med Toxicol. 2009;5(4):223-225.

    Sildenafil

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

Reported for Fever Bark but not commonly for Sildenafil: an allergic reaction, heart failure, anxiety or restlessness and mood changes or irritability.

Effects for Sildenafil come from the ADVERSE REACTIONS section of its FDA label; effects for Fever Bark 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.

Overlapping uses

What Sildenafil Is Prescribed For, and What Fever Bark Has Been Studied For

These two come up together because they touch the same health topic — not because they do the same job. Sildenafil is a prescription medicine with approved uses on its FDA label. Fever Bark is a supplement: what follows is what researchers have looked at it for, and how strong that evidence is.

Sildenafil is prescribed for: Sildenafil treats two distinct conditions depending on the product. Viagra (tablet) and Vybrique (dissolving oral film) are approved for erectile dysfunction (ED) — difficulty getting or keeping an erection. Generic sildenafil tablets and oral film are also approved for ED. Revatio and several generic sildenafil products (tablets, oral suspension, and injection) are used for pulmonary arterial hypertension (PAH) — high blood pressure in the arteries of the lungs — in adults to improve exercise ability and slow the disease from getting worse.

Read the rest of what Sildenafil is prescribed for

Revatio oral suspension and injection are also approved for PAH in children ages 1 to 17.

Fever Bark has been studied for:

  • Hypertension studied, not established Fever Bark has been studied for this. Natural Medicines rates the evidence: Insufficient Reliable Evidence To Rate Read what the research shows

    Fever Bark for hypertension

    Although there is interest in using oral fever bark for hypertension, there is insufficient reliable information about the clinical effects of fever bark for this condition.

Effectiveness ratings and the research summaries above are the verbatim record from the Natural Medicines database, which grades evidence from “Effective” down to “Insufficient Reliable Evidence To Rate”. A rating below the top of that scale means researchers have looked at it — not that it works, and never that it can stand in for a prescribed medicine. Do not stop or replace Sildenafil on your own; if you are taking Fever Bark for the same health topic, tell your prescriber, especially if the medicine is being adjusted to a target.

From our Q&A

Questions About Fever Bark or Sildenafil

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

This page covers Fever Bark only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Sildenafil page lists 160 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), American Mistletoe (major), Grapefruit (major), Hawthorn (major) and St. John's Wort (major).

By severity: 5 major · 114 moderate · 41 minor.

From our pharmacist’s overview on the Sildenafil page

“Sildenafil relaxes blood vessels, whether prescribed as Revatio for pulmonary hypertension or as Viagra, and that blood-pressure-lowering action makes this list one to treat with genuine care. Of the 160 supplement and herbal ingredients on file, five carry a major rating, and those deserve understanding first.”

Reviewed by 2 · Jul 18, 2026

Open the Sildenafil interaction page

How much people look this up

Where Fever Bark and Sildenafil 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 Fever Bark
Steady interest

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

29 days ago today
Medication Sildenafil
Top half

#716 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 Fever Bark reference on this page ↓
  • Freshness: we automatically re-check this combination every week — this pair was last verified September 13, 2026. The Fever Bark and Sildenafil 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 Fever Bark

What is Fever Bark?

Fever Bark
  • Fever
  • Diarrhea
  • Malaria (traditional)
  • Digestive complaints
  • Bitter tonic

Fever bark is the bark of the Australian tree Alstonia constricta, used in traditional medicine for fever, diarrhea, and infections. There is very little reliable human research to support these uses, and the bark contains potent alkaloids that may cause serious side effects. It is best avoided unless used under direct medical supervision.

Alstonia constricta · Apocynaceae · Bark · Bark powder, tincture, liquid extract, capsules

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

Fever Bark: dosing

There is no well-established, standardized dose for fever bark. Because the bark contains potent alkaloids that vary between products, a safe and effective dose has not been reliably determined in modern research.If a product is used at all, follow the directions on the label and do not exceed them.

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

Read the full Fever Bark monograph & all interactions
Medication

About Sildenafil

What Is Sildenafil Used For?

Brand name: Revatio

Sildenafil treats two distinct conditions depending on the product. Viagra (tablet) and Vybrique (dissolving oral film) are approved for erectile dysfunction (ED) — difficulty getting or keeping an erection. Generic sildenafil tablets and oral film are also approved for ED.

Revatio and several generic sildenafil products (tablets, oral suspension, and injection) are used for pulmonary arterial hypertension (PAH) — high blood pressure in the arteries of the lungs — in adults to improve exercise ability and slow the disease from getting worse. Revatio oral suspension and injection are also approved for PAH in children ages 1 to 17.

Most-Reported Side Effects for Sildenafil

From FAERS, the FDA’s public side-effect reporting system (126,564 reports, all brands). Reports are voluntary and are not proof the drug caused the effect.

Dyspnea 13,327 reports
Headache 10,220 reports
Diarrhea 7,049 reports
Nausea 6,489 reports
Fatigue 6,390 reports
See full Sildenafil drug information
Keep checking

Other Drugs & Fever Bark

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

40Major
674Moderate
87Minor
2,028No known interaction
40 Major 674 Moderate 87 Minor 2,028 No interaction
Major

40 interactions

Moderate

674 interactions

Showing 60 of 674 moderate interactions — see all 674 on the Fever Bark page.

Minor

87 interactions

Showing 60 of 87 minor interactions — see all 87 on the Fever Bark page.

No interaction 2,028 drugs checked — show the list

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

Showing the 60 most looked-up of 2,028 medications checked with no known interaction — see the full Fever Bark list.

See the full Fever Bark interactions page
See every supplement checked against Sildenafil, ranked by severity
Evidence & sources

Fever Bark References

The 50 references that drive our Fever Bark 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. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
  2. Foster S, Tyler VE. Tyler's Honest Herbal: A Sensible Guide to the Use of Herbs and Related Remedies. 3rd ed., Binghamton, NY: Haworth Herbal Press, 1993.
  3. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
  4. Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
  5. McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
  6. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
  7. Ellenhorn MJ, et al. Ellenhorn's Medical Toxicology: Diagnoses and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams & Wilkins, 1997.
  8. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
  9. Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
  10. Sklar S, et al. Drug therapy screening system. Indianapolis, IN: First Data Bank 99.1-99. 2 eds.
  11. Teloken C, Rhoden EL, Sogari P, et al. Therapeutic effects of high dose yohimbine hydrochloride on organic erectile dysfunction. J Urol 1998;159:122-4. PubMed
  12. Jacobsen FM. Fluoxetine-induced sexual dysfunction and an open trial of yohimbine. J Clin Psychiatry 1992;53:119-22.
  13. Hollander E, McCarley A. Yohimbine treatment of sexual side effects induced by serotonin reuptake blockers. J Clin Psychiatry 1992;53:207-9.
  14. Kearney T, Tu N, Haller C. Adverse drug events associated with yohimbine-containing products: a retrospective review of the California Poison Control System reported cases. Ann Pharmacother 2010;44:1022-9. PubMed
  15. VandenBrink, B. M., Foti, R. S., Rock, D. A., Wienkers, L. C., and Wahlstrom, J. L. Prediction of CYP2D6 drug interactions from in vitro data: evidence for substrate-dependent inhibition. Drug Metab Dispos. 2012;40(1):47-53. 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 Fever Bark and Sildenafil Together: Common Questions

Is it safe to take Fever Bark with Sildenafil?
We do not list a known interaction between Fever Bark and Sildenafil. 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 Fever Bark and Sildenafil 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.
Are Fever Bark and Sildenafil used for the same thing?
They overlap in purpose, which usually means the real question is whether you need both rather than whether they are safe together. This page lists the shared uses and how strong the evidence is for Fever Bark in each. That is a conversation for your prescriber, especially if Sildenafil is being adjusted to a target.
How was the Fever Bark and Sildenafil combination checked?
Interactions in our licensed database are recorded against drug classes. Sildenafil is filed under 6 classifications, and Fever Bark has documented interactions with 9 drug classes — none of Sildenafil'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 Fever Bark interact with any other medications?
Yes. Fever Bark has 801 documented drug interactions in our database — Sildenafil 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 Sildenafil interact with any supplements?
Yes. Sildenafil has documented interactions with 160 supplements in our database — Fever Bark is not one of them. The Sildenafil 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

Fever Bark monograph Uses, safety profile, and every drug interaction in one place Sildenafil drug information The full plain-English guide to this medication Sildenafil supplement interactions Every supplement checked against Sildenafil, 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 50 citations behind this page Ask a pharmacist Free, personal answer from our licensed team

Still Have a Question About Sildenafil and Fever Bark?

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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.