Drug & supplement interaction

Fever Bark + Levothyroxine

Levothyroxine brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, and others.

No Known Interaction

Medically reviewed by Dr. Brian Staiger, PharmD, BCPS · Updated July 2026 · Pair last verified Sep 13, 2026

The bottom line No known interaction

We found no known interaction between Fever Bark and Levothyroxine 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 Levothyroxine 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

Fever Bark and Levothyroxine

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 Levothyroxine 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 Levothyroxine and Fever Bark? Ask Dr. Brian Staiger, PharmD, BCPS directly ›

How we checked

Why No Interaction Is Listed for Levothyroxine

Interactions in our licensed database are recorded against drug classes, not just single drug names. Levothyroxine is filed under 3 classifications — including thyroid hormone, oral drugs. 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 Levothyroxine’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 — Levothyroxine 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. Levothyroxine)

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 Levothyroxine 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. 4 of them are worth acting on rather than waiting out — marked below.

Heart failure Worth acting on Additional detail
Fever Bark
“The yohimbine constituent of fever bark, when taken alone in high doses, can cause hypertension, cardiac conduction abnormalities, and cardiac failure, It is not known if these effects occur with fever bark.”

Fever Bark · Natural Medicines adverse-effect record, reported in hypertension.
4 sources cited

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

86856. Brodde, O. E., Anlauf, M., Arroyo, J., Wagner, R., Weber, F., and Buck, K. D. Hypersensitivity of adrenergic receptors and blood-pressure response to oral yohimbine in orthostatic hypotension. N.Engl.J Med 4-28-1983;308(17):1033-1034. PubMed

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

86896. Riley AJ, Goodman R, Kellett JM, and et al. Double blind trial of yohimbine hydrochloride in the treatment of erection inadequacy. Sexual Marital Ther 1989;4(1):17-26. DOI
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Wheezing Worth acting on 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

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

86825. Landis, E. and Shore, E. Yohimbine-induced bronchospasm. Chest 1989;96(6):1424. PubMed

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.

15. McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.

94328. Lobay D. Rauwolfia in the Treatment of Hypertension. Integr Med (Encinitas). 2015 Jun;14(3):40-6.
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Seizures Worth acting on 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

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

3971. Hollander E, McCarley A. Yohimbine treatment of sexual side effects induced by serotonin reuptake blockers. J Clin Psychiatry 1992;53:207-9.

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

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.

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

86804. Myers, A. and Barrueto, F., Jr. Refractory priapism associated with ingestion of yohimbe extract. J Med Toxicol. 2009;5(4):223-225.
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
An allergic reaction Worth acting on Additional detail
Fever Bark
“The yohimbine constituent of fever bark, when taken alone, causes allergic reactions (2,5,6,11,18). It is not known if this occurs with fever bark.”

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

2. Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.

5. 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.

6. The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.

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.

18. Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Mood changes or irritability / Anxiety or restlessness / Trouble sleeping / Tiredness Additional detail
Fever Bark
“The yohimbine constituent of fever bark, when taken alone, causes malaise, fatigue, irritability insomnia, restlessness, agitation, and anxiety. The reserpine constituent of fever bark, when taken alone, causes depression (17). It is not known if these effects occur with fever bark.”

Fever Bark · Natural Medicines adverse-effect record, reported in anxiety.
6 sources cited

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

3970. Jacobsen FM. Fluoxetine-induced sexual dysfunction and an open trial of yohimbine. J Clin Psychiatry 1992;53:119-22.

3971. Hollander E, McCarley A. Yohimbine treatment of sexual side effects induced by serotonin reuptake blockers. J Clin Psychiatry 1992;53:207-9.

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

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

86801. Giampreti, A., Lonati, D., Locatelli, C., Rocchi, L., and Campailla, M. T. Acute neurotoxicity after yohimbine ingestion by a body builder. Clin Toxicol.(Phila) 2009;47(8):827-829. PubMed
Levothyroxine

Listed in the ADVERSE REACTIONS section of the FDA label for Levothyroxine. Read the label on DailyMed ›
Fever Additional detail

Fever Bark

“Orally, no adverse effects have been reported with fever bark; however, a thorough evaluation of safety outcomes has not been conducted. Theoretically, fever bark might cause the known adverse effects of its constituents, reserpine and yohimbine, and should be used with caution.”

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

Levothyroxine

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

3970. Jacobsen FM. Fluoxetine-induced sexual dysfunction and an open trial of yohimbine. J Clin Psychiatry 1992;53:119-22.

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

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.

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

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

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
Levothyroxine

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

Showing the 10 most notable of 11 shared effects — ranked by how unusual each one is, not just whether both lists mention it.

Reported for Fever Bark but not commonly for Levothyroxine: stomach upset, a stuffy or runny nose, raised blood pressure and muscle pain.

Effects for Levothyroxine 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.

How to take them

Some Levothyroxine Products Have a Food Rule — Fever Bark Should Not Break It

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach. Most supplements — Fever Bark included — are taken with a meal, so the easy mistake is swallowing both together at breakfast. Where that rule applies, keep Levothyroxine on its own and move Fever Bark to a meal later in the day.

This may not be true of your version. Food instructions belong to the product, not the ingredient: two Levothyroxine 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.

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 Fever Bark or Levothyroxine

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 Levothyroxine, 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 Levothyroxine

This page covers Fever Bark only. If you take other supplements — a multivitamin, a sleep aid, something for joints — the Levothyroxine page lists 50 supplements it has a documented interaction with, worst first, each one explained.

The most serious there right now: Activated Charcoal (major), Tiratricol (major), Acetyl-l-carnitine (moderate), Alpha-lipoic Acid (moderate) and Ascophyllum Nodosum (moderate).

By severity: 2 major · 39 moderate · 9 minor.

From our pharmacist’s overview on the Levothyroxine page

“Levothyroxine replaces a hormone your body measures in tiny amounts, so small shifts in its blood level show up in how you feel, and I treat this list with genuine care. Nearly everything on it does one of two things: blocks the pill from being absorbed in the gut, the way everyday minerals like calcium do by binding it into complexes,…”

Reviewed by 2 · Jul 18, 2026

Open the Levothyroxine interaction page

How much people look this up

Where Fever Bark and Levothyroxine 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

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

29 days ago today

Medication Levothyroxine

Top 10

#2 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 Levothyroxine 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 Dr. Brian Staiger, PharmD, BCPS.

Supplement

About Fever Bark

What is 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 Levothyroxine

What Is Levothyroxine Used For?

Brand names: Euthyrox, Levothroid, Unithroid, Synthroid, Levoxyl, Levo-T, Eltroxin, Estre, Levothyroxine, Novothyrox, Levolet

Levothyroxine replaces or supplements the thyroid hormone your body isn't making enough of. It's used for hypothyroidism — an underactive thyroid — in adults, children, and even newborns, whether the cause is the thyroid gland itself, the pituitary gland, or the hypothalamus in the brain.

It's also used alongside surgery and radioiodine treatment in people with certain types of thyroid cancer, to help suppress the hormone that can stimulate cancer growth. It is not meant for weight loss, treating benign thyroid nodules in people who have enough iodine, or for hypothyroidism during recovery from a temporary condition called subacute thyroiditis.

See full Levothyroxine 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 Levothyroxine, 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.

Blumenthal M, ed. The Complete German Commission E Monographs: Therapeutic Guide to Herbal Medicines. Trans. S. Klein. Boston, MA: American Botanical Council, 1998.
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.
The Review of Natural Products by Facts and Comparisons. St. Louis, MO: Wolters Kluwer Co., 1999.
Leung AY, Foster S. Encyclopedia of Common Natural Ingredients Used in Food, Drugs and Cosmetics. 2nd ed. New York, NY: John Wiley & Sons, 1996.
McGuffin M, Hobbs C, Upton R, Goldberg A, eds. American Herbal Products Association's Botanical Safety Handbook. Boca Raton, FL: CRC Press, LLC 1997.
McEvoy GK, ed. AHFS Drug Information. Bethesda, MD: American Society of Health-System Pharmacists, 1998.
Ellenhorn MJ, et al. Ellenhorn's Medical Toxicology: Diagnoses and Treatment of Human Poisoning. 2nd ed. Baltimore, MD: Williams & Wilkins, 1997.
Gruenwald J, Brendler T, Jaenicke C. PDR for Herbal Medicines. 1st ed. Montvale, NJ: Medical Economics Company, Inc., 1998.
Brinker F. Herb Contraindications and Drug Interactions. 2nd ed. Sandy, OR: Eclectic Medical Publications, 1998.
Sklar S, et al. Drug therapy screening system. Indianapolis, IN: First Data Bank 99.1-99. 2 eds.
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
Jacobsen FM. Fluoxetine-induced sexual dysfunction and an open trial of yohimbine. J Clin Psychiatry 1992;53:119-22.
Hollander E, McCarley A. Yohimbine treatment of sexual side effects induced by serotonin reuptake blockers. J Clin Psychiatry 1992;53:207-9.
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
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
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.
Mustonen, P., Savola, J., and Lassila, R. Atipamezole, an imidazoline-type alpha(2)-adrenoceptor inhibitor, binds to human platelets and inhibits their adrenaline-induced aggregation more effectively than yohimbine. Thromb.Res 8-1-2000;99(3):231-237.
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
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.
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
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
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
Giampreti, A., Lonati, D., Locatelli, C., Rocchi, L., and Campailla, M. T. Acute neurotoxicity after yohimbine ingestion by a body builder. Clin Toxicol.(Phila) 2009;47(8):827-829. PubMed
Myers, A. and Barrueto, F., Jr. Refractory priapism associated with ingestion of yohimbe extract. J Med Toxicol. 2009;5(4):223-225.
Berlin, I., Crespo-Laumonnier, B., Cournot, A., Landault, C., Aubin, F., Legrand, J. C., and Puech, A. J. The alpha 2-adrenergic receptor antagonist yohimbine inhibits epinephrine-induced platelet aggregation in healthy subjects. Clin Pharmacol.Ther. 199
Cimolai, N. and Cimolai, T. Yohimbine use for physical enhancement and its potential toxicity. J Diet.Suppl 2011;8(4):346-354. PubMed
Bagheri, H., Berlan, M., Montastruc, J. L., and Montastruc, P. Yohimbine and lacrimal secretion. Br J Clin Pharmacol. 1990;30(1):151-152.
Landis, E. and Shore, E. Yohimbine-induced bronchospasm. Chest 1989;96(6):1424. PubMed
Susset, J. G., Tessier, C. D., Wincze, J., Bansal, S., Malhotra, C., and Schwacha, M. G. Effect of yohimbine hydrochloride on erectile impotence: a double-blind study. J Urol. 1989;141(6):1360-1363. PubMed
Chatelut, E., Rispail, Y., Berlan, M., and Montastruc, J. L. Yohimbine increases human salivary secretion. Br.J Clin Pharmacol. 1989;28(3):366-368. PubMed
Montastruc, P., Berlan, M., and Montastruc, J. L. Effects of yohimbine on submaxillary salivation in dogs. Br J Pharmacol 1989;98(1):101-104. PubMed
Charney, D. S., Price, L. H., and Heninger, G. R. Desipramine-yohimbine combination treatment of refractory depression. Implications for the beta-adrenergic receptor hypothesis of antidepressant action. Arch.Gen.Psychiatry 1986;43(12):1155-1161. PubMed
Braddock, L., Cowen, P. J., Elliott, J. M., Fraser, S., and Stump, K. Binding of yohimbine and imipramine to platelets in depressive illness. Psychol.Med 1986;16(4):765-773. PubMed
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.
Boon, N. A., Elliott, J. M., Grahame-Smith, D. G., John-Green, T., and Stump, K. A comparison of alpha 2-adrenoreceptor binding characteristics of intact human platelets identified by [3H]-yohimbine and [3H]- dihydroergocryptine. J Auton.Pharmacol 1983;3
Brodde, O. E., Anlauf, M., Arroyo, J., Wagner, R., Weber, F., and Buck, K. D. Hypersensitivity of adrenergic receptors and blood-pressure response to oral yohimbine in orthostatic hypotension. N.Engl.J Med 4-28-1983;308(17):1033-1034. PubMed
Charney, D. S., Heninger, G. R., and Redmond, D. E., Jr. Yohimbine induced anxiety and increased noradrenergic function in humans: effects of diazepam and clonidine. Life Sci. 7-4-1983;33(1):19-29. PubMed
Knoll, L. D., Benson, R. C., Jr., Bilhartz, D. L., Minich, P. J., and Furlow, W. L. A randomized crossover study using yohimbine and isoxsuprine versus pentoxifylline in the management of vasculogenic impotence. J Urol. 1996;155(1):144-146. DOI
Bagheri, H., Chale, J. J., Guyen, L. N., Tran, M. A., Berlan, M., and Montastruc, J. L. Evidence for activation of both adrenergic and cholinergic nervous pathways by yohimbine, an alpha 2-adrenoceptor antagonist. Fundam.Clin Pharmacol 1995;9(3):248-254.
Morgan, C. A., III, Southwick, S. M., Grillon, C., Davis, M., Krystal, J. H., and Charney, D. S. Yohimbine-facilitated acoustic startle reflex in humans. Psychopharmacology (Berl) 1993;110(3):342-346. PubMed
Biaggioni, I., Robertson, R. M., and Robertson, D. Manipulation of norepinephrine metabolism with yohimbine in the treatment of autonomic failure. J Clin Pharmacol. 1994;34(5):418-423. PubMed
Mann, K., Klingler, T., Noe, S., Roschke, J., Muller, S., and Benkert, O. Effects of yohimbine on sexual experiences and nocturnal penile tumescence and rigidity in erectile dysfunction. Arch.Sex Behav. 1996;25(1):1-16. PubMed
Rowland, D. L., Kallan, K., and Slob, A. K. Yohimbine, erectile capacity, and sexual response in men. Arch Sex Behav 1997;26(1):49-62.
Bremner, J. D., Innis, R. B., Ng, C. K., Staib, L. H., Salomon, R. M., Bronen, R. A., Duncan, J., Southwick, S. M., Krystal, J. H., Rich, D., Zubal, G., Dey, H., Soufer, R., and Charney, D. S. Positron emission tomography measurement of cerebral metaboli
Riley AJ, Goodman R, Kellett JM, and et al. Double blind trial of yohimbine hydrochloride in the treatment of erection inadequacy. Sexual Marital Ther 1989;4(1):17-26. DOI
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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 Levothyroxine Together: Common Questions

Is it safe to take Fever Bark with Levothyroxine?

We do not list a known interaction between Fever Bark and Levothyroxine. 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 Levothyroxine 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 Fever Bark and Levothyroxine at the same time of day?

At least one FDA label for a product containing Levothyroxine says to take it on an empty stomach, and supplements are usually taken with a meal — so taking them together at breakfast is the easy mistake. Where that applies, keep Levothyroxine on its own and move Fever Bark to a meal later in the day. Food instructions belong to the product rather than the ingredient, so check the directions on your own box. This is about absorption, not an interaction.

How was the Fever Bark and Levothyroxine combination checked?

Interactions in our licensed database are recorded against drug classes. Levothyroxine is filed under 3 classifications, and Fever Bark has documented interactions with 9 drug classes — none of Levothyroxine'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 — Levothyroxine 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 Levothyroxine interact with any supplements?

Yes. Levothyroxine has documented interactions with 50 supplements in our database — Fever Bark is not one of them. The Levothyroxine interaction page linked on this page lists every one, ranked by severity.

Written and reviewed by the HelloPharmacist editorial staff. Our editorial policy

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

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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.