✅ Bactrim DS (800/160 mg) Tablet: Uses, Dosage, Side Effects & Antibiotic Guide

What is Bactrim DS?

Bactrim DS is a combination antibiotic medication containing sulfamethoxazole and trimethoprim. It is primarily used to treat bacterial infections such as urinary tract infections, respiratory tract infections, ear infections, traveler’s diarrhea, and certain types of pneumonia. Bactrim DS works by inhibiting the growth of bacteria, and the combination of sulfamethoxazole and trimethoprim provides broader coverage against a variety of bacteria.

✅ Indications (Uses)

Bactrim DS is a broad-spectrum antibiotic used to treat a variety of bacterial infections, especially those caused by susceptible strains. It is commonly prescribed for:

• Cystitis
• Pyelonephritis
• Acute bronchitis
• Pneumocystis pneumonia (PCP) – especially in HIV/AIDS patients
• Otitis media in children
• Chronic bronchitis exacerbations
• MRSA-related abscesses or cellulitis (off-label)
• Pneumocystis jirovecii pneumonia (PCP) prophylaxis in immunocompromised individuals

Not effective against viral infections like flu or COVID-19.

⚙️ Mechanism of Action

Bactrim DS is a combination of two antibiotics that work synergistically:

• Sulfamethoxazole: Inhibits dihydropteroate synthase, blocking folate production in bacteria
• Trimethoprim: Inhibits dihydrofolate reductase, further preventing DNA synthesis

Together, they block sequential steps in bacterial folate metabolism, making Bactrim bactericidal (kills bacteria).

🕒 Dosage & Administration

📌 Typical Adult Dosage:

• 1 Bactrim DS tablet (800/160 mg) every 12 hours
• Take with a full glass of water
• Duration varies from 3 to 14 days depending on the infection

📌 PCP Treatment (High Dose):

• Up to 15–20 mg/kg/day of Trimethoprim component in divided doses

Always follow the dosage prescribed by your healthcare provider. Do not self-adjust.

⚠️ Side Effects

Common Side Effects:

• Nausea or vomiting
• Loss of appetite
• Skin rash
• Diarrhea
• Headache

Serious (Rare) Side Effects:

• Stevens-Johnson syndrome (SJS) or toxic epidermal necrolysis (TEN)
• Severe hypersensitivity reactions
• Blood disorders (e.g., anemia, leukopenia, thrombocytopenia)
• Hyperkalemia
• Liver damage
• Kidney dysfunction

Stop medication and seek urgent care for rash, jaundice, persistent fever, or difficulty breathing.

🛑 Warnings & Precautions

• Do not use if allergic to sulfa drugs
• Use cautiously in patients with kidney or liver disease
• Monitor for electrolyte imbalances (esp. potassium)
• May increase risk of crystalluria – drink plenty of fluids
• Risk of hemolysis in patients with G6PD deficiency
• Not recommended in pregnancy (especially 1st and 3rd trimesters)
• Use with caution in elderly and immunocompromised patients

🔄 Drug Interactions

May interact with:

• Warfarin – may increase bleeding risk
• ACE inhibitors/ARBs – may raise potassium
• Methotrexate – increased toxicity
• Phenytoin – increased serum levels
• Diuretics (esp. thiazides) – increased risk of thrombocytopenia in elderly

📦 Storage Instructions

• Store at room temperature (20–25°C / 68–77°F)
• Keep tablets in original packaging
• Protect from heat and moisture
• Keep away from children