Tyrothricin
The first antibiotic mixture taken from a soil bacterium, still used in throat lozenges and wound gels outside the US
Tyrothricin is a mixture of peptides made by the soil bacterium Brevibacillus (formerly Bacillus) brevis: cyclic tyrocidines and linear gramicidins. Described in 1941, it was one of the first antibiotics put to clinical use, and it is used only on the skin and in the mouth and throat. German pharmacies sell it without a prescription in wound gels and powders and, combined with an antiseptic and a local anaesthetic, in sore-throat lozenges. It has no US approval.
Used in human trials: 0.1% powder (0.1 g per 100 g), Twice a day, Topical (Study: infected or at-risk skin wounds, 131 adults (randomised, pla...) Details ↓
Recommended Dosing
Used in human trials
There is no FDA label. A label from outside the US exists (see the regulatory status on this page) but was not read for this page: these are amounts given in published trials, not recommendations.
What is it?
Tyrothricin is not one molecule but the crude antibacterial fraction of a soil bacterium. In 1941 René Dubos and Rollin Hotchkiss reported that aerobic spore-forming bacilli from soil, sewage and cheese made an alcohol-soluble substance, tyrothricin, that killed many bacteria, and that it could be split into two crystalline parts. One, tyrocidine, behaved like a general antiseptic that lost much of its power in the presence of tissue; the other, gramicidin, worked only on Gram-positive bacteria but kept its activity when applied to an infected site. Those two families of peptides, the cyclic tyrocidines and the linear gramicidins, are still what tyrothricin is.
The mixture acts on bacteria, fungi and some viruses, and its gramicidin component lowers the electrical potential across bacterial membranes and lets potassium leak out. It is used only on surfaces and is not given to be swallowed or injected; the tyrocidines, tested apart from the mixture, were toxic to mammalian cells and red blood cells at micromolar concentrations in a culture study listed under References. In laboratory tests of clinical strains from 2003, all the Gram-positive bacteria tested, including methicillin-resistant Staphylococcus aureus, were inhibited at 4 mg/L or less, and Candida yeasts at higher concentrations. A Taiwanese survey of MRSA isolates gave the same MIC90 of 4 µg/mL. Bacteria have found it hard to become resistant to it, though a 2020 study did coax a small, stable rise in resistance from Klebsiella and found cross-resistance to some other antibiotics afterwards.
Today it appears in two kinds of product, both sold in German pharmacies without a prescription. The wound gel and powder contain tyrothricin alone at 1 mg per gram and are labelled for small, superficial, slightly weeping wounds such as cuts and grazes. The sore-throat lozenge combines 0.5 mg tyrothricin with the antiseptic benzalkonium chloride and the local anaesthetic benzocaine; its label says the tyrothricin is not absorbed. The combination lozenge has its own placebo-controlled trial, which is listed under References because it tested three active ingredients together.
Trials of tyrothricin alone are few and small. In a randomised multicentre trial, a 0.1% powder applied twice daily for nine days to infected or at-risk skin wounds sped healing modestly over placebo powder. In 33 volunteers with standardised forearm abrasions, the 0.1% gel helped healing, but no more than the same gel without tyrothricin, so the gel base did most of the work. In 24 people with acne, a 0.1% tyrothricin preparation reduced lesions on one half of the face, less than benzoyl peroxide products but with fewer side effects. Older studies in volunteers showed that a 10 mg tyrothricin lozenge left high gramicidin levels in saliva for a short time and cut mouth bacteria about a hundredfold.
Its place in throat medicine is debated. A 2019 systematic review of local antibiotics for sore throat found sparse, mostly poor evidence and questioned whether antibiotics belong in over-the-counter throat products at all, since most sore throats are viral. A 2025 laboratory study found that tyrothricin at concentrations reached during use could weaken the killing action of aminoglycoside antibiotics on some gut bacteria.
Tyrothricin has never been approved in the United States; Drugs@FDA holds no application. Gramicidin, one of its components, is approved in the US as part of an eye-drop combination, and it has its own entry here. Tyrocidines purified from tyrothricin have shown strong activity against malaria parasites in culture, but those studies tested separated components rather than the mixture.
Mechanism of Action
Tyrothricin acts on microbial membranes; it is applied only to skin and the throat, where the German lozenge label says it is not absorbed.
Membrane effects
It inhibits Gram-positive bacteria and yeasts; its gramicidin component lowers bacterial membrane potential and causes potassium leakage.
Slow resistance
Clinical strains collected after decades of use were still fully susceptible, though one laboratory study raised resistance a little in Klebsiella.
Immune effects
In mouse immune cells it triggered interleukin-1 beta release through an inflammasome, and in human blood cells it strongly suppressed mitogen-driven proliferation.
Published Research
These are studies of tyrothricin itself, read from their PubMed abstracts: small trials of the wound powder, gel and an acne preparation, volunteer studies of lozenges and a gargle, a prescribing study, laboratory work on bacteria, parasites and immune cells, one animal study and reviews. Trials of combination lozenges and studies of tyrocidines purified from the mixture are listed under References only.
Wound powder versus placebo
In a randomised, double-blind multicentre trial of 131 adults with infected or at-risk traumatic or surgical skin wounds, 0.1% tyrothricin powder applied twice daily for nine days shrank wounds slightly faster than placebo powder (0.55 against 0.47 mm a day in radius) and lowered a wound index more; adverse events were equally few.
Wound gel: the base did the work
Thirty-three healthy volunteers had three standard abrasions on the forearm, treated with tyrothricin 0.1% gel, the same gel without tyrothricin, or nothing. Both gels improved healing over no treatment and did so equally, so adding tyrothricin did not interfere with healing but did not add to it.
Acne: a split-face comparison
In an observer-blind trial in 24 people with papulopustular acne, tyrothricin 0.1% on one side of the face was compared with clindamycin plus benzoyl peroxide or with benzoyl peroxide 5% on the other. It reduced inflammatory and non-inflammatory lesions, less than the comparators, and caused fewer product-related adverse events than benzoyl peroxide.
Saliva gramicidin rises with the dose
Peak gramicidin in saliva was highest after sucking a lozenge containing 10 mg tyrothricin (about 109 mg/L), lower after a gargle containing 667 mg per litre (21 mg/L) and lowest after a 4 mg lozenge (14 mg/L).
How long lozenge gramicidin stays in the mouth
In healthy volunteers, gramicidin in saliva peaked at an average 37.5 mg/L within about five minutes of sucking a tyrothricin lozenge, and 44% of it was recovered in saliva within 30 minutes; only about 11% of a gargle stayed in the mouth.
No acquired resistance after decades of use
Clinical isolates collected in 2003 from skin and mucous membranes, 20 strains each of eight species, were tested. All Gram-positive bacteria, including MRSA, were inhibited at 4 mg/L or less and Candida species at 16 to 32 mg/L, with no acquired resistance found.
MRSA in Taiwan
In 223 MRSA isolates from Taiwanese hospitals collected in 2009 and 2010, the concentration of tyrothricin that inhibited 90% of strains was 4 µg/mL, against 0.12 µg/mL for mupirocin.
Active against Toxoplasma in culture
Tyrothricin stopped Toxoplasma gondii multiplying at under 100 nM, with tyrocidine A the active part and gramicidin A inactive, but it also harmed fibroblasts, T cells and zebrafish embryos at 1 µM, and parasites recovered after the early damage.
Stronger with chitosan
Combined with the polysaccharide chitosan in a film-forming base, tyrothricin's MIC against methicillin-resistant and susceptible Staphylococcus aureus fell to a thirty-third and a quarter of its value alone, and the pair also acted on Pseudomonas, which tyrothricin alone did not inhibit.
Chitosan film gel in rat wounds
In rat burn, abrasion, incision and excision wounds, a chitosan film-forming gel containing tyrothricin healed wounds better than no treatment and better than a commercial tyrothricin gel or fusidate ointment, an effect the authors credited to the film's cover.
An underrated topical antibiotic
A review describes tyrothricin as a mixture of tyrocidines and gramicidins with activity against bacteria, fungi and some viruses and very little tendency to induce resistance, currently used in sore-throat medicines and for small infected wounds, and argues for testing it in other skin infections.
Dosing Data
Tyrothricin is used only on the skin and in the mouth and throat. These are the amounts used in published human studies, as their abstracts state them. The German licensed products state strengths rather than doses: 1 mg per gram in the wound gel and powder (German Fachinformation, November 2020) and 0.5 mg per lozenge, combined with two other actives, in the throat lozenge (German Fachinformation, August 2023).
Educational information, not medical advice. Each dose above is tagged with its source: an approved label, a published human study, animal data, or amounts reported by users. None is a recommendation for you. An unapproved compound has no established safe or effective human dose, and products sold for “research use only” are not made or tested for people. Talk to a doctor before acting on anything on this site, including before you start, stop or change any medicine or dose. Full medical disclaimer.
What a Buyer Needs to Know
What is sold, how it is mixed, stored and taken, and what is known about its safety, quality and legal status. Each part names its source. Where we have none, it says unknown.
What is sold
Unknown: we hold no label and no published test that says what forms or vial sizes Tyrothricin is sold in. A vial's own label is a seller's claim, not a source.
Mixing a vial: a worked example
No worked example: none of the doses on this page is a fixed amount in mg or mcg injected under the skin or into a muscle (the routes given are: oromucosal, topical). There is no home-mixing step to show. The reconstitution calculator does the arithmetic for any vial.
Source: the route and amount of each dose row in Dosing Data below.
Storage before and after mixing
Unknown: no label or published stability study on file says how to store Tyrothricin, before or after mixing. The mixing guide sets out the general rules, with their sources: keep a mixed vial in the fridge, and use it promptly, as the bacteriostatic water label says of any drug dissolved in it. The 28 days often quoted is the limit for an opened multiple-dose vial from a manufacturer, an outer limit set for sterility, not a time a mixed solution has been shown to keep. Nobody has published how long Tyrothricin stays intact once mixed.
How it is taken
As it was given in human studies: Topical (Twice a day; Study: infected or at-risk skin wounds, 131 adults (randomised, placebo-controlled)); Oromucosal (One lozenge, sucked; Study: oral bacteria in saliva, 12 volunteers (crossover)).
For injection technique, sites and needle disposal, see the mixing guide.
Source: Used in human trials: the route and frequency of each row in Dosing Data below.
What to expect, and when
How long it stays in the body: not established by a measurement cited on this entry.
How long the doses were given: Study: infected or at-risk skin wounds, 131 adults (randomised, placebo-controlled): 9 days; Study: standard forearm abrasions, 33 volunteers: Followed for 12 days; Study: oral bacteria in saliva, 12 volunteers (crossover): Single use, 1 hour observed.
When effects appear: unknown; no source on this page gives a time to effect for Tyrothricin. Results reported in the studies are under Published Research.
Source: Used in human trials, the duration of each row in Dosing Data below.
Side effects, and when to stop or get help
From the Side Effects section: Very rare allergic skin reactions, including burning with the gel (Tyrosur Fachinformation, November 2020); Fewer product-related adverse events than benzoyl peroxide in an acne trial (PMID 26458265); Adverse events no more frequent than placebo powder in a wound trial (PMID 15587588); In the combination lozenge, allergic reactions and methaemoglobinaemia are attributed to its benzocaine (Dorithricin Fachinformation, August 2023). Full list and cautions ↓
When to stop or get help: unknown; no label or trial on file sets rules for stopping Tyrothricin. Treat a severe or unexpected reaction as a reason to stop and see a doctor.
Source: the Side Effects section below (“From the German labels and the studies above”).
Interactions
Unknown: a PubMed search for human interaction studies of Tyrothricin (reviewed 2026-10-28) found none. Unknown is not the same as safe to combine.
Every peptide's record, with its source: the interaction matrix.
Checking what you bought
Unknown: no published independent test of Tyrothricin products is in our lab-results database yet, so how products sold under this name measure up is not known.
To read a certificate of analysis, paste it into the COA decoder. Trust & Verification explains what independent testing can and cannot show.
Legal status
US: Not FDA Approved (Not approved in the US: Drugs@FDA holds no application (searched October 28, 2026), and it is not on the EMA's central medicines list). Elsewhere: approved in Used outside the US in sore-throat lozenges and wound preparations (Pharmazie review, 2016; phase 4 lozenge trial NCT03323528). Sport: Not on the 2026 List.
Country by country ↓ · Regulatory tracker
Source: this entry's approval status and the WADA Prohibited List, as in Legal Status below.
Side Effects & Contraindications
Reported Side Effects
From the German labels and the studies above.
Contraindications & Cautions
Cautions from the labels and the evidence.
Legal Status
Tyrothricin is a licensed pharmacy medicine in Germany, sold without a prescription, and has no US approval.
Frequently Asked Questions
?What is tyrothricin?
A mixture of antibacterial peptides, cyclic tyrocidines and linear gramicidins, made by the soil bacterium Brevibacillus brevis. It was described in 1941 and is one of the oldest antibiotics still in use.
?Is tyrothricin available without a prescription?
In Germany, yes: its wound gel and powder and a combination throat lozenge are pharmacy medicines that do not need a prescription, according to their German product information. It is not approved in the United States.
?Why is tyrothricin only used on the skin and throat?
Its products are made for surfaces: the German labels cover small wounds and the throat, and the lozenge label says the tyrothricin in it is not absorbed. Its tyrocidine components, tested on their own, were toxic to mammalian and red blood cells in culture.
?Do tyrothricin lozenges work for sore throat?
A placebo-controlled trial found that a lozenge combining tyrothricin with an antiseptic and a local anaesthetic relieved sore throat, but that tests the combination, not tyrothricin alone. A systematic review found the evidence for local antibiotics in sore throat weak, and most sore throats are viral.
?Can bacteria become resistant to tyrothricin?
Rarely. Clinical strains collected after decades of use were still fully susceptible, though one laboratory study selected a small, stable rise in resistance in Klebsiella.
?How is tyrothricin related to gramicidin?
Gramicidin is one of its two components. Gramicidin on its own has a separate entry, and it is approved in the US only as part of a combination eye drop.
References
- [clinical-trial] Bayerl C, et al. "[Tyrothricin powder in the treatment of cutaneous lesions]." Pharmazie, 2004;59(11):864-8. PMID: 15587588.
- [clinical-trial] Wigger-Alberti W, et al. "Efficacy of a tyrothricin-containing wound gel in an abrasive wound model for superficial wounds." Skin Pharmacol Physiol, 2013;26(1):52-6. PMID: 23183356.
- [clinical-trial] Richter C, et al. "Reduction of Inflammatory and Noninflammatory Lesions with Topical Tyrothricin 0.1% in the Treatment of Mild to Severe Acne Papulopustulosa: A Randomized Controlled Clinical Trial." Skin Pharmacol Physiol, 2016;29(1):1-8. PMID: 26458265.
- [clinical-trial] Matula C, et al. "Decontamination of the oral cavity. Effect of six local anti-microbial preparations in comparison to water and parafilm as controls." J Int Med Res, 1988;16(2):98-106. PMID: 3378662.
- [pubmed] Matula C, et al. "Salivary levels of gramicidin after use of a tyrothricin-containing gargle/mouth-wash and tyrothricin lozenges." Int J Clin Pharmacol Res, 1988;8(4):259-61. PMID: 2460410.
- [pubmed] Kreuzig F, et al. "Salivary levels of gramicidin after use of a tyrothricin lozenge and a tyrothricin gargle/mouth-wash." Int J Clin Pharmacol Res, 1983;3(2):65-70. PMID: 6207119.
- [pubmed] Hedenmalm K, et al. "Effect of withdrawal of fusafungine from the market on prescribing of antibiotics and other alternative treatments in Germany: a pharmacovigilance impact study." Eur J Clin Pharmacol, 2019;75(7):979-984. PMID: 30838424.
- [pubmed] Dubos RJ, et al. "THE PRODUCTION OF BACTERICIDAL SUBSTANCES BY AEROBIC SPORULATING BACILLI." J Exp Med, 1941;73(5):629-40. PMID: 19871101.
- [pubmed] Stauss-Grabo M, et al. "Decade-long use of the antimicrobial peptide combination tyrothricin does not pose a major risk of acquired resistance with gram-positive bacteria and Candida spp." Pharmazie, 2014;69(11):838-41. PMID: 25985581.
- [pubmed] Chen YH, et al. "Trends in the susceptibility of methicillin-resistant Staphylococcus aureus to nine antimicrobial agents, including ceftobiprole, nemonoxacin, and tyrothricin: results from the Tigecycline In Vitro Surveillance in Taiwan (TIST) study, 2006-2010." Eur J Clin Microbiol Infect Dis, 2014;33(2):233-9. PMID: 23955154.
- [pubmed] Wesgate R, et al. "Understanding the risk of emerging bacterial resistance to over the counter antibiotics in topical sore throat medicines." J Appl Microbiol, 2020;129(4):916-925. PMID: 32352619.
- [pubmed] Robertson A, et al. "Over-the-counter antibiotics compromising aminoglycoside activity." J Antimicrob Chemother, 2025;80(1):87-94. PMID: 39471310.
- [pubmed] Amdouni Y, et al. "Potential Molecular Targets of the Broad-Range Antimicrobial Peptide Tyrothricin in the Apicomplexan Parasite Toxoplasma gondii." Biomedicines, 2026;14(1). PMID: 41595705.
- [pubmed] Maeda M, et al. "Suppressive effects of peptide antibiotics against proliferation and cytokine production in mitogen-activated human peripheral-blood mononuclear cells." Arzneimittelforschung, 2011;61(12):734-41. PMID: 22282962.
- [pubmed] Allam R, et al. "Cutting edge: cyclic polypeptide and aminoglycoside antibiotics trigger IL-1β secretion by activating the NLRP3 inflammasome." J Immunol, 2011;186(5):2714-8. PMID: 21278344.
- [pubmed] Han SD, et al. "Chitosan-Based Film of Tyrothricin for Enhanced Antimicrobial Activity against Common Skin Pathogens Including Staphylococcus aureus." J Microbiol Biotechnol, 2016;26(5):953-8. PMID: 26907760.
- [pubmed] Kim JY, et al. "Wound healing efficacy of a chitosan-based film-forming gel containing tyrothricin in various rat wound models." Arch Pharm Res, 2015;38(2):229-38. PMID: 24715576.
- [review] Lang C, et al. "Tyrothricin--An underrated agent for the treatment of bacterial skin infections and superficial wounds?." Pharmazie, 2016;71(6):299-305. PMID: 27455547.
- [review] Essack S, et al. "Topical (local) antibiotics for respiratory infections with sore throat: An antibiotic stewardship perspective." J Clin Pharm Ther, 2019;44(6):829-837. PMID: 31407824.
- [review] Korting HC, et al. "Antimicrobial peptides and skin: a paradigm of translational medicine." Skin Pharmacol Physiol, 2012;25(6):323-34. PMID: 22964878.
- [clinical-trial] Palm J, et al. "Efficacy and safety of a triple active sore throat lozenge in the treatment of patients with acute pharyngitis: Results of a multi-centre, randomised, placebo-controlled, double-blind, parallel-group trial (DoriPha)." Int J Clin Pract, 2018;72(12):e13272. PMID: 30329199.
- [pubmed] Vladimirova TY, et al. "[Treatment of acute tonsillopharyngitis in elderly patients: aspects of complex topical therapy]." Vestn Otorinolaringol, 2025;90(4):19-26. PMID: 40899887.
- [pubmed] Leussa AN, et al. "Antiplasmodial Cyclodecapeptides from Tyrothricin Share a Target with Chloroquine." Antibiotics (Basel), 2022;11(6). PMID: 35740207.
- [pubmed] Rautenbach M, et al. "Inhibition of malaria parasite blood stages by tyrocidines, membrane-active cyclic peptide antibiotics from Bacillus brevis." Biochim Biophys Acta, 2007;1768(6):1488-97. PMID: 17462586.
- [pubmed] BRODIE HR. "A TREATMENT FOR SEBORRHEA CAPITIS (CRADLE CAP)." Can Med Assoc J, 1964;90(3):136-7. PMID: 14118686.
- [registry] ClinicalTrials.gov API v2, read October 28, 2026: NCT03323528 (phase 4, sore-throat lozenge containing tyrothricin, completed) and NCT01227759 (phase 2, tyrothricin gel in wound healing, completed).
- [other] US FDA, Drugs@FDA (openFDA): no application for tyrothricin. Read October 28, 2026.
- [other] Tyrosur Wundheilgel and Wundheilpuder, German Fachinformation (summary of product characteristics), November 2020: tyrothricin 1 mg/g; pharmacy-only. Not on DailyMed: no US approval. Read October 29, 2026. https://www.fachinfo.de/pdf/002857
- [other] Dorithricin Halstabletten Classic, German Fachinformation, August 2023: per lozenge tyrothricin 0.5 mg, benzalkonium chloride 1.0 mg, benzocaine 1.5 mg; pharmacy-only, not prescription-only. Not on DailyMed: no US approval. Read October 29, 2026. https://fachinfo.de/pdf/003793
Sources & Citations
Every study on this page was read from its PubMed record on October 28 or 29, 2026. The German product information was read on fachinfo.de on October 29, 2026; US status comes from Drugs@FDA and EU status from the EMA list. Searches recorded on October 28, 2026: PubMed tyrothricin[tiab] 349 records; ClinicalTrials.gov 0 records naming it (the lozenge and gel trials cited name their products); Drugs@FDA and the EMA list 0. Grey Peptides sells nothing and links to no vendor.
Medical Disclaimer: This content is for educational and informational purposes only. It is not medical advice, and nothing here is an instruction to obtain or use any compound. Talk to a licensed clinician about your own situation.