Use - Respiratory infections - exacerbation of chronic bronchitis, treatment and prevention (primary and secondary) of pneumonia caused by Pneumocystis jirovecii in adults and children. - Sinusitis, acute otitis media. - Gastrointestinal infections: typhoid fever and paratyphoid, bacterial dysentery (shigellosis), diarrhea, cholera. - Acute and chronic urinary tract and prostate infections (urethritis, cystitis, prostatitis). - Chancroid. - Brucellosis, osteomyelitis, nocardiosis, actinomycosis, toxoplasmosis, and South American blastomycosis (possibly in combination with other antibiotics). - Biseptol is indicated for use in adult patients, adolescents, children, and infants older than 6 weeks. Contraindications - Hypersensitivity to active substances, sulfonamides, trimethoprim, co-trimoxazole, or any of the excipients of the drug. - Concomitant use with dofetilide. - Severe liver or kidney dysfunction (creatinine clearance below 15 ml/min). - Megaloblastic anemia due to folic acid deficiency. - Treatment of streptococcal angina. - Pregnancy and breastfeeding period. - Co-trimoxazole should not be used in infants during the first 6 weeks of life.