What Is Tetracycline? Uses, Dosage, and What You Need to Know in 2026

Tetracycline is one of the oldest broad-spectrum antibiotics still in clinical use today. First discovered in the 1940s and widely used since the 1950s, it laid the groundwork for an entire class of antibiotics — the tetracyclines — that includes doxycycline, minocycline, and newer agents like tigecycline and omadacycline. In 2026, tetracycline itself remains a clinically relevant drug for specific indications, though doxycycline has become the preferred agent for most everyday uses.

What Is Tetracycline Used For?

Tetracycline is a broad-spectrum bacteriostatic antibiotic — meaning it stops bacteria from multiplying rather than killing them outright. It is FDA-approved for treating a wide range of bacterial infections, including:

• Acne (moderate-to-severe, adjunctive oral therapy)
• Sexually transmitted infections: chlamydia, gonorrhea, syphilis
• Respiratory tract infections (pneumonia, bronchitis)
• Urinary tract infections caused by susceptible bacteria
• Rickettsial infections (Rocky Mountain spotted fever, typhus, Q fever)
• Lyme disease (early stages)
• Brucellosis (with streptomycin)
• H. pylori eradication (as part of bismuth quadruple therapy with bismuth, metronidazole, and a PPI)
• Plague and tularemia (bioterrorism threats)
• Anthrax (inhalational, post-exposure) when other agents are not suitable

What Dosage Form Does Tetracycline Come In?

In 2026, tetracycline is available as oral capsules in two strengths:

• 250 mg capsules (tetracycline hydrochloride, USP)
• 500 mg capsules (tetracycline hydrochloride, USP)

Intravenous and intramuscular formulations are no longer commercially available. Brand names include Sumycin and Panmycin, though only generics are actively manufactured in 2026, primarily by Amneal Pharmaceuticals.

What Is the Typical Tetracycline Dosage?

Dosage depends on the condition being treated. Common adult regimens include:

• General bacterial infections: 250–500 mg taken 4 times daily (every 6 hours) or 500 mg twice daily.
• Acne: Start at 500 mg–1 g/day in divided doses. Reduce to 125–500 mg/day as maintenance once improvement occurs.
• Chlamydia: 500 mg 4 times daily for at least 7 days.
• Brucellosis: 500 mg 4 times daily for 3 weeks, with streptomycin in the first 1–2 weeks.

Important: Never exceed 2 g/day (2,000 mg). Dose reduction is required in patients with significant renal impairment. Always follow your prescriber's specific instructions.

How Should Tetracycline Be Taken?

Tetracycline has strict administration requirements that affect its effectiveness:

• Empty stomach required: Take at least 1 hour before or 2 hours after meals. Food, dairy, and several mineral supplements dramatically reduce absorption.
• Full glass of water: Take with at least 8 ounces (240 mL) of water. This reduces the risk of esophageal irritation and ulceration.
• Stay upright: Remain sitting, standing, or walking for at least 30 minutes after each dose.
• Avoid dairy, antacids, calcium, iron, zinc: These bind to tetracycline through chelation and reduce absorption by up to 50–70%. Separate antacids or supplements by at least 2–6 hours.
• Complete the full course: Even if you feel better before finishing, stopping early increases the risk of treatment failure and antibiotic resistance.

Who Should NOT Take Tetracycline?

• Pregnant women (FDA Category D — fetal risk)
• Children under 8 years old (permanent tooth discoloration, bone effects)
• Patients with significant renal impairment (requires dose adjustment, use with caution)
• Patients taking isotretinoin or acitretin (increased intracranial hypertension risk — contraindicated)

For a complete list of what to avoid while taking Tetracycline, see: Tetracycline Drug Interactions: What to Avoid and What to Tell Your Doctor.