Tetracycline
SUMYCIN
Pronunciation: tet-ra-SYE-kleen
“Some mice Tetris cycling”
What it isInhibitor of the 30S ribosomal subunit; H. pylori regimens, rickettsial and atypical infection.
Why this oneRemains part of bismuth quadruple therapy for resistant H. pylori.
What limits itFour-times-daily dosing on an empty stomach, and cations block absorption. Avoid in pregnancy and young children.
Tetracycline prescription history
Animated chart of estimated U.S. prescriptions per year, Tetracycline antibacterials (1949–2026). Tetracycline enters in 1953 (estimated).
FDA-approved for
- bacterial infections (1953)
- acne (1953)
Principal riskFour-times-daily on an empty stomach; cations block it
Classes and tags
Clinical profile
Legacy pregnancy categoryD
Defining liabilityAllergy, gastrointestinal effects and agent-specific renal, hepatic, hematologic or interaction risks.
FDA label
Read the full label on DailyMed ↗
NO BOXED WARNINGS
| FDA dosing | Population | Start | Target | Max |
|---|---|---|---|---|
| Susceptible bacterial infections | Adults | 500 mg BID or 250 mg QID | 500 mg BID or 250 mg QID | 500 mg QID (severe/unresponsive infections) |
| Susceptible bacterial infections | Pediatric >8 yr | 25–50 mg/kg/day (10–20 mg/lb) divided QID | 25–50 mg/kg/day divided QID | 50 mg/kg/day |
| Acne (moderate–severe, adjunctive long-term) | Adults | 1 g/day in divided doses | Maintenance 125–500 mg/day | 1 g/day |
Renal Reduce total dosage in renal impairment (lower individual doses and/or extend dosing intervals)
Hepatic Undefined
Instructions
- Take with adequate fluid to reduce esophageal irritation/ulceration; avoid dosing at bedtime
- Avoid antacids (aluminum/calcium/magnesium), iron, zinc, sodium bicarbonate, food, and dairy — they impair absorption
- Avoid during tooth development (pregnancy through age 8) — permanent tooth discoloration
- For streptococcal infections continue therapy for 10 days
Available strengths
- cap 250, 500 mg
- tab 250, 500 mg
- sol 30 mg/mL
- ointment 30 mg/mL
- spray 30 mg/mL
Cautions
- Permanent tooth discoloration and enamel hypoplasia during tooth development
- Esophagitis and esophageal ulceration (esp. capsule taken at bedtime)
- Hepatotoxicity/liver failure, especially with renal impairment
- Photosensitivity
- Increased BUN (dose-related)
- Superinfection/Candida overgrowth
Adverse reactions
- Nausea
- Vomiting
- Diarrhea
- Epigastric distress
- Glossitis / dysphagia
- Rash
- Photosensitivity
- Tooth discoloration
Pregnancy Undefined
Lactation Undefined
Cost
Generic entry1985
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Memory aids: interaction avatars
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Self-check
- Which H. pylori regimen still includes tetracycline?
Bismuth quadruple therapy. - What blocks tetracycline absorption?
Cations.