Is Trimethoprim-Sulfamethoxazole a controlled substance?

Trimethoprim-Sulfamethoxazole is not federally scheduled in the US. Controlled-drug status differs by country — verify your local rules.

Trimethoprim-Sulfamethoxazole

US brand names:Bactrim, TMS

Also known as: Trimethoprim-Sulphamethoxazole, Co-trimoxazole

Calculate dosage

Sourced from published veterinary references. Awaiting credentialed clinical reviewer — our editorial process.

Trimethoprim-Sulfamethoxazole is dosed at 15–25 mg/kg/day IM q24h for 7 to 14 days in bearded dragons, per Plumb's Veterinary Drug Handbook, 10th ed (2023, held copy; the original seed cited the 9th, which was never consulted), Sulfa-/Trimethoprim monograph, REPTILES section entry c), printed p.1196 (corpus PDF p.1223), superscript 46 → Lewbart. Reptile formulary. Presented at: Atlantic Coast Veterinary Conference; 2001 — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207; Invertebrate Medicine — ISBN 9781119569435, https://openlibrary.org/isbn/9781119569435. Verify against current literature before clinical use.

Drug Class

Antibiotic

Routes

POSC

Indications

AntibacterialanticoccidialBacterial cystitis - complicated UTI (extra-label)Bacterial cystitis/UTI (complicated)Bacterial infection (broad spectrum)Bacterial infection (potentiated sulfonamide)Bacterial infections Broad-spectrum bacterial infectionBroad-spectrum potentiated sulfonamidechronic skincoccidia coccidiosisComplicated bacterial cystitis (UTI)Dermal hemangiosarcoma (infected wound)General bacterialNocardia infectionsPneumocystis pneumoniaprostatitisRespiratory infections

Mechanism of Action

Sequential blockade of folate synthesis: sulfamethoxazole inhibits dihydropteroate synthase; trimethoprim inhibits dihydrofolate reductase.

Side effects & warnings

May cause keratoconjunctivitis sicca (KCS) in dogs with prolonged use. Can cause bone marrow suppression. Avoid in animals with hepatic disease. Adequate hydration required.

Species with Trimethoprim-Sulfamethoxazole dosing data (33 dose rules)

African Grey Parrot African Pygmy Hedgehog Bearded Dragon Blue-and-Gold Macaw Canary Cat (Domestic)Chicken (Poultry)Chinchilla Dog (Domestic)Domestic Pigeon Ferret Green-cheeked Conure Guinea Pig

Evidence levels across 33 dose rules

Moderate×20Weak×5Extrapolated×2Anecdotal×2Strong×4

Each ExoticRx dose rule is graded by the strength of its primary evidence — see the editorial process.

Backed by 25 published sources

· 236. Dorrestein GM. Studies on Pharmacokinetics of Some Antibacterial Agents in Homing Pigeons (Columba livia), Thesis: Utrecht University; 1986. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.422 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.1 (Antimicrobial Agents Used in Birds.a). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929
· 241. Dorrestein GM. Passerine and softbill therapeutics. Vet Clin North Am Exot Anim Pract. 2000;3:35-57. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.422 doi:10.1016/s1094-9194(17)30094-4 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.1 (Antimicrobial Agents Used in Birds.a). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929

Sample dosing (2 of 33 cited rules)

A dog/cat sample is shown here. Cited dosing for all 21 species — reptiles, birds, pocket pets, livestock, and equine — is free on the per-species pages above. Pro adds the weight-based calculator for every species.

Species	Route	Dose	Frequency	Evidence	Source
Dog (Domestic)	PO	15–30 mg/kg	q12h	Strong	Hillier A, Lloyd DH, Weese JS, et al. Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (antimicrobial guidelines working group of the international society for companion animal infectious diseases). Vet Dermatol. 2014;25(3):163-e43. — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1222 (2026-08-01). — LOCATOR CONVENTION 2026-08-07: the bare 'p.1222' in this citation is the PDF index of the held scan, not the printed page. The PRINTED page is p.1195; verified by finding the drug named there. If you are holding the book, turn to p.1195. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207
Cat (Domestic)	PO	15–30 mg/kg	q12h	Strong

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Calculate Dosage for Trimethoprim-Sulfamethoxazole

59. Bauck L, Hoefer HL. Avian antimicrobial therapy. Semin Avian Exot Pet Med. 1993;2:17-22. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.422 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.1 (Antimicrobial Agents Used in Birds.a). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929

· 802. Samour J. Pharmaceutics commonly used in avian medicine. In: Samour J, eds. Avian Medicine; Mosby, Philadelphia, PA; 2000:388-418. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.422 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.1 (Antimicrobial Agents Used in Birds.a). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929; Avian Medicine (Samour) — ISBN 9780723438328, https://openlibrary.org/isbn/9780723438328

· Bauck L, Hoefer HL. Avian antimicrobial therapy. Semin Avian Exot Pet Med. 1993;2:17-22. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.422 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.1 (Antimicrobial Agents Used in Birds.a). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929

· Bodley K. Appendix 4. Drug Formulary. In: Vogelnest L, Portas T, eds. Current Therapy in Medicine of Australian Mammals; CSIRO Publishing, Clayton South, Vic; 2019:702-727.; Morrisey JK, Carpenter JW, et al. Formulary. In: Quesenberry KE, Orcutt CJ, Mans C, et al. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, 4th ed., Elsevier, St. Louis, MO; 2021:620-630. — Verified against Carpenter's Exotic Animal Formulary, 6th Ed, p.705 (2026-08-01). — figure located 2026-08-05 at Carpenter's 6th ed, Table 15.3 (Antimicrobial Therapy Used in Exotic Animals According to Site of Infection.a,b); the page cited previously does not carry it. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929; Clinical Guide to Fish Medicine — ISBN 9781119259558, https://openlibrary.org/isbn/9781119259558; Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery — ISBN 9780323484350, https://openlibrary.org/isbn/9780323484350

· Carpenter's Exotic Animal Formulary, 6th Ed — Carpenter's Exotic Animal Formulary 6th ed, Table 10.1 (Antimicrobial Agents Used in Rabbits.a). Located 2026-08-05: the only table covering this species in which the drug's own row prints this dose. The copy held is an ebook conversion with no printed page numbers, so the table is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929

· Carpenter's Exotic Animal Formulary, 6th Ed — Carpenter's Exotic Animal Formulary 6th ed, Table 5.4 (Antiparasitic Agents Used in Birds). Located 2026-08-05: the only table covering this species in which the drug's own row prints this dose. The copy held is an ebook conversion with no printed page numbers, so the table is the citable location. — located 2026-08-05 in Carpenter's Exotic Animal Formulary 6th ed, Table 5.4 (Antiparasitic Agents Used in Birds); the earlier note claiming no held source contained this figure was wrong and has been removed. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929

· Dorrestein GM. Passerine and softbill therapeutics. Vet Clin North Am Exot Anim Pract. 2000;3:35-57. — Source: Carpenter's Exotic Animal Formulary, 6th Ed, p.422 doi:10.1016/s1094-9194(17)30094-4 — Carpenter's Exotic Animal Formulary 6th ed, Table 5.1 (Antimicrobial Agents Used in Birds.a). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929

· EQUISUL-SDT - Sulfadiazine and Trimethoprim Suspension [US Product Label for Horses]. Aurora Pharmaceutical, Inc.; 2021. https://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?setid=434cfb08-bb19-46fc-a55d-b9ecf0bec601; Winther L, Guardabassi L, Baptiste KE, Friis C. Antimicrobial disposition in pulmonary epithelial lining fluid of horses. Part I. Sulfadiazine and trimethoprim. J Vet Pharmacol Ther. 2011;34(3):277-284. doi:10.1111/j.1365-2885.2010.01229.x — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1223 (2026-08-01). — LOCATOR CONVENTION 2026-08-07: the bare 'p.1223' in this citation is the PDF index of the held scan, not the printed page. The PRINTED page is p.1196; verified by finding the drug named there. If you are holding the book, turn to p.1196. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207

· Gibbons PM, Klaphake E, Carpenter JW. Reptiles. In: Carpenter JW, ed. Exotic Animal Formulary. 4th ed. St. Louis: Elsevier; 2013:83-182. — Verified against Mader's Reptile and Amphibian Medicine and Surgery, 3rd Ed, p.1404 (2026-08-01). — Carpenter's Exotic Animal Formulary 6th ed, Table 4.1 (Antimicrobial Agents Used in Reptiles.a,b). Located 2026-08-05: the only table covering this species in which the drug's own row prints this dose. The copy held is an ebook conversion with no printed page numbers, so the table is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929; Mader's Reptile and Amphibian Medicine and Surgery (Divers & Stahl) — ISBN 9780323482530, https://openlibrary.org/isbn/9780323482530 | 2026-08-13 RE-ANCHOR: the supporting row is carpenter Table 4.4 (Antiparasitic Agents Used in Reptiles), "Trimethoprim-sulfonamides | 30 mg/kg PO q24 x2-14 days87,243 | Most species/coccidia, although this […]", with the block header "avoid potentiated sulfa drugs in cases of dehydration or renal dysfunction331". The previously cited Table 4.1 does NOT support this rule: its only 30 mg/kg PO trimethoprim-sulphonamide row is scoped "Bearded dragon" at q12h x14 days, and its trimethoprim/sulfamethoxazole row is "30 mg/kg IM q24h264 | Reticulated python". CORRECTION to this rule's own notes: mader printed p.1194 does NOT print "30 mg/kg, PO, IM, IV, q 24 h" - it prints "10-30 mg/kg PO q24h99 | Most species/maintain hydration" and, chelonian-specific, "30 mg/kg IM q24h x 2 days, then q48h311 | Tortoises/PD". No IV route, and the PO figure is a RANGE.

· Greenacre, C.B., Luna, G.L., and Morishita, T.M. (2018). Backyard poultry and waterfowl. In: Exotic Animal Formulary, 5e (ed. J.W. Carpenter), 377-432. St. Louis, Missouri: Elsevier. — Source: Greenacre & Morishita, Backyard Poultry Medicine and Surgery, 2nd Ed, p.589 — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929; Backyard Poultry Medicine and Surgery — ISBN 9781119511755, https://openlibrary.org/isbn/9781119511755

· Hayes P. Diseases of chinchillas. In: Kirk's Current Veterinary Therapy: XIII Small Animal Practice. WB Saunders; 2000:1152-1157. — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1223 (2026-08-01). — LOCATOR CONVENTION 2026-08-07: the bare 'p.1223' in this citation is the PDF index of the held scan, not the printed page. The PRINTED page is p.1196; verified by finding the drug named there. If you are holding the book, turn to p.1196. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207

· Hillier A, Lloyd DH, Weese JS, et al. Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (antimicrobial guidelines working group of the international society for companion animal infectious diseases). Vet Dermatol. 2014;25(3):163-e43. — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1222 (2026-08-01). — LOCATOR CONVENTION 2026-08-07: the bare 'p.1222' in this citation is the PDF index of the held scan, not the printed page. The PRINTED page is p.1195; verified by finding the drug named there. If you are holding the book, turn to p.1195. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207

· Hillyer EV, Brown SA. Ferrets. In: Birchard SJ, Sherding RG, eds. Saunders Manual of Small Animal Practice; WB Saunders, Philadelphia, PA; 1994:1317-1344. — Verified against Carpenter's Exotic Animal Formulary, 6th Ed, p.934 (2026-08-01). — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929

· Hoefer HL. Hedgehogs. Vet Clin North Am Small Anim Pract. — Verified against Carpenter's Exotic Animal Formulary, 6th Ed, p.734 (2026-08-01). — Carpenter's Exotic Animal Formulary 6th ed, Table 8.1 (Antimicrobial Agents Used in Hedgehogs). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — SOURCE EDITION: Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929

· Meredith A. BSAVA Small Animal Formulary: Part B: Exotic Pets, British Small Animal Veterinary Association, Quedgeley, Gloucester, UK; 2015. / 130. Morrisey JK, Carpenter JW. Formulary. In: Quesenberry KE, Carpenter JW, eds. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, 4th ed., Elsevier, St. Louis, MO; 2021:620-630. — Verified against Carpenter's Exotic Animal Formulary, 6th Ed, p.774 (2026-08-01). — SOURCE EDITION: BSAVA Small Animal Formulary, Part B — Exotic Pets — ISBN 9781910443712, https://openlibrary.org/isbn/9781910443712; Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929; Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery — ISBN 9780323484350, https://openlibrary.org/isbn/9780323484350

· Meredith A. BSAVA Small Animal Formulary: Part B: Exotic Pets, British Small Animal Veterinary Association, Quedgeley, Gloucester, UK; 2015.; Morrisey JK, Carpenter JW. Formulary. In: Quesenberry KE, Carpenter JW, eds. Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery, 4th ed., Elsevier, St. Louis, MO; 2021:620-630. — Verified against Carpenter's Exotic Animal Formulary, 6th Ed, p.774 (2026-08-01). — SOURCE EDITION: BSAVA Small Animal Formulary, Part B — Exotic Pets — ISBN 9781910443712, https://openlibrary.org/isbn/9781910443712; Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929; Ferrets, Rabbits, and Rodents: Clinical Medicine and Surgery — ISBN 9780323484350, https://openlibrary.org/isbn/9780323484350

· Plumb DC. Plumb's Veterinary Drug Handbook, 9th ed., Wiley Blackwell, Ames, IA; 2018. — Verified against Carpenter's Exotic Animal Formulary, 6th Ed, p.845 (2026-08-01). — Carpenter's Exotic Animal Formulary 6th ed, Table 10.1 (Antimicrobial Agents Used in Rabbits.a). The copy held is an ebook conversion with no printed page numbers, so the table — not the page — is the citable location. — EDITION NOTE 2026-08-06: this rule's Plumb's reference names the 9th edition, which is not held and was never consulted. The held copy is the 10th ed (2023). The Plumb's line was never confirmed against the held edition, so rely on it only as background; any other source named in this citation is unaffected. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207; Carpenter's Exotic Animal Formulary — ISBN 9780323833929, https://openlibrary.org/isbn/9780323833929

· Plumb's Veterinary Drug Handbook, 10th ed (2023, held copy; the original seed cited the 9th, which was never consulted), Sulfa-/Trimethoprim monograph, REPTILES section entry c), printed p.1196 (corpus PDF p.1223), superscript 46 → Lewbart. Reptile formulary. Presented at: Atlantic Coast Veterinary Conference; 2001 — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207; Invertebrate Medicine — ISBN 9781119569435, https://openlibrary.org/isbn/9781119569435

· Plumb's Veterinary Drug Handbook, 10th ed (2023, held copy; the original seed cited the 9th, which was never consulted), Sulfa-/Trimethoprim, printed p.1195 (corpus p.1222), DOGS — 'Superficial bacterial folliculitis (extra-label): 15 - 30 mg/kg PO twice daily.31' and 'Complicated UTI: 15 - 30 mg/kg PO every 12 hours32'. Superscript 31 = Hillier A, Lloyd DH, Weese JS, et al. Guidelines for the diagnosis and antimicrobial therapy of canine superficial bacterial folliculitis (ISCAID Antimicrobial Guidelines Working Group). Vet Dermatol. 2014;25(3):163-e43. Superscript 32 = Weese JS, Blondeau J, Boothe D, et al. ISCAID guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats. Vet J. 2019;247:8-25. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207

· Plumb's Veterinary Drug Handbook, 10th ed (2023, held copy; the original seed cited the 9th, which was never consulted), p.1223 (Sulfa-/Trimethoprim, Dosages, CATS); corroborated by BSAVA Small Animal Formulary 10th Ed Part A p.419 'Dogs, Cats: 15-30 mg/kg p.o. q12h' — SOURCE EDITION: BSAVA Small Animal Formulary, Part A — Canine and Feline — ISBN 9781910443705, https://openlibrary.org/isbn/9781910443705; Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207 — Plumb's Veterinary Drug Handbook, 10th ed (held), Sulfa-/Trimethoprim monograph, printed p.1196 (corpus PDF p.1223), CATS: "Bacterial cystitis (extra-label): ... b) Complicated UTI: 15 - 30 mg/kg PO every 12 hours."; same monograph, printed p.1195: "Unless otherwise noted, doses are for combined sulfa-/trimethoprim." [INDICATION, DURATION AND NOTES CORRECTED 2026-08-12, two readers — the previous notes carried an SC instruction on a PO row; the only printed feline SC figure, BSAVA printed p.419, is 30 mg/kg s.c. q24h, not q12h.]

· Plumb's Veterinary Drug Handbook, 9th Ed, p.1223 (Sulfa-/Trimethoprim, Dosages, HORSES) — EDITION NOTE 2026-08-06: this rule's Plumb's reference names the 9th edition, which is not held and was never consulted. The held copy is the 10th ed (2023). The Plumb's line was never confirmed against the held edition, so rely on it only as background; any other source named in this citation is unaffected. — LOCATOR CONVENTION 2026-08-07: the bare 'p.1223' in this citation is the PDF index of the held scan, not the printed page. The PRINTED page is p.1196; verified by finding the drug named there. If you are holding the book, turn to p.1196. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207

· Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1223 (2026-08-01). — LOCATOR CONVENTION 2026-08-07: the bare 'p.1223' in this citation is the PDF index of the held scan, not the printed page. The PRINTED page is p.1196; verified by finding the drug named there. If you are holding the book, turn to p.1196. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207

· Weese JS, Blondeau J, Boothe D, et al. International Society for Companion Animal Infectious Diseases (ISCAID) guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats. Vet J. 2019;247:8-25. doi:10.1016/j.tvjl.2019.02.008 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1222 (2026-08-01). — LOCATOR CONVENTION 2026-08-07: the bare 'p.1222' in this citation is the PDF index of the held scan, not the printed page. The PRINTED page is p.1195; verified by finding the drug named there. If you are holding the book, turn to p.1195. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207

Weese JS, Blondeau J, Boothe D, et al. International Society for Companion Animal Infectious Diseases (ISCAID) guidelines for the diagnosis and management of bacterial urinary tract infections in dogs and cats. Vet J. 2019;247:8-25. doi:10.1016/j.tvjl.2019.02.008 — Verified against Plumb's Veterinary Drug Handbook, 10th Ed, p.1223 (2026-08-01). — LOCATOR CONVENTION 2026-08-07: the bare 'p.1223' in this citation is the PDF index of the held scan, not the printed page. The PRINTED page is p.1196; verified by finding the drug named there. If you are holding the book, turn to p.1196. — SOURCE EDITION: Plumb's Veterinary Drug Handbook — ISBN 9781394172207, https://openlibrary.org/isbn/9781394172207