Tetracycline is a time-tested, broad-spectrum antibiotic belonging to the tetracycline class, widely utilized in clinical practice for its efficacy against a diverse range of gram-positive and gram-negative bacteria, as well as atypical pathogens. It functions by inhibiting bacterial protein synthesis at the ribosomal level, effectively halting microbial proliferation. This agent is particularly valued for its utility in treating acne vulgaris, respiratory tract infections, and certain zoonotic diseases, making it a versatile tool in the antimicrobial arsenal. Proper usage requires consideration of bacterial susceptibility, patient factors, and potential drug interactions to maximize therapeutic outcomes while minimizing risks.

Features

• Active Ingredient: Tetracycline hydrochloride
• Drug Class: Tetracycline antibiotic
• Available Forms: Oral capsules (250 mg, 500 mg), tablets, topical formulations
• Mechanism of Action: Binds to the 30S ribosomal subunit, inhibiting aminoacyl-tRNA attachment
• Spectrum of Activity: Effective against many gram-positive and gram-negative bacteria, Rickettsia, Chlamydia, Mycoplasma, and some protozoa
• Half-Life: Approximately 6–12 hours, permitting twice-daily dosing in most cases

Benefits

• Provides broad-spectrum coverage for a variety of bacterial and atypical infections
• Effective long-term management for moderate to severe inflammatory acne
• Oral and topical formulations allow flexible administration routes
• Cost-effective compared to many newer antibiotics
• Well-established safety and efficacy profile with decades of clinical use
• Useful in resource-limited settings due to stability and affordability

Common use

Tetracycline is commonly prescribed for bacterial infections such as pneumonia, bronchitis, sinusitis, and urinary tract infections caused by susceptible organisms. It is also indicated for acne vulgaris, rosacea, Lyme disease, cholera, brucellosis, and infections caused by Rickettsia (e.g., Rocky Mountain spotted fever), Chlamydia (e.g., psittacosis, trachoma), and Mycoplasma pneumoniae. Off-label uses may include periodontal disease and Helicobacter pylori eradication in combination therapy.

Dosage and direction

Dosage must be individualized based on infection severity, pathogen susceptibility, and patient renal function. For most infections in adults: 500 mg orally twice daily or 250 mg four times daily. For acne: 500 mg to 1 gram daily in divided doses, often tapered after initial response. Take on an empty stomach (1 hour before or 2 hours after meals) with a full glass of water to enhance absorption and reduce gastrointestinal irritation. Do not take with dairy products, antacids, or iron supplements, as these significantly reduce bioavailability. Duration of therapy typically ranges from 7 to 14 days for infections, and several weeks to months for acne.

Precautions

Avoid use in pregnancy and breastfeeding due to risk of fetal harm and tooth discoloration in infants. Use with caution in patients with renal impairment; dosage adjustment may be necessary. Tetracycline may cause photosensitivity—advise patients to use sunscreen and protective clothing. Prolonged use can lead to superinfection (e.g., candidiasis, Clostridium difficile-associated diarrhea). Monitor for signs of hepatotoxicity, especially with high doses or extended therapy. Not recommended for children under 8 years due to permanent tooth discoloration and potential effects on bone growth.

Contraindications

Hypersensitivity to tetracycline or any component of the formulation. Severe hepatic dysfunction. Concomitant use of isotretinoin. Pregnancy and breastfeeding. Children under 8 years of age.

Possible side effect

Common side effects include nausea, vomiting, diarrhea, epigastric distress, glossitis, dysphagia, and enterocolitis. Photosensitivity reactions, skin rash, and urticaria may occur. Less frequently, esophagitis and esophageal ulceration have been reported, especially when capsules are taken with insufficient water. Rare but serious adverse effects include hepatotoxicity, pancreatitis, blood dyscrasias, intracranial hypertension (pseudotumor cerebri), and lupus erythematosus exacerbation. Long-term use may result in tooth discoloration (yellow-gray-brown) in children and occasionally in adults.

Drug interaction

Tetracycline may interact with antacids containing aluminum, calcium, or magnesium; iron preparations; and bismuth subsalicylate, reducing its absorption. Concurrent use with oral contraceptives may decrease contraceptive efficacy. Potentiates the effect of oral anticoagulants (e.g., warfarin). Avoid concomitant administration with penicillin, as tetracycline may antagonize its bactericidal effect. May increase lithium levels and the risk of methotrexate toxicity. Use with retinoids may increase the risk of intracranial hypertension.

Missed dose

If a dose is missed, take it as soon as remembered unless it is almost time for the next dose. Do not double the dose to catch up. Maintaining consistent blood levels is important for efficacy, especially in acute infections.

Overdose

Symptoms of overdose may include nausea, vomiting, and diarrhea. In severe cases, hepatotoxicity and pancreatitis can occur. Management is supportive; there is no specific antidote. Gastric lavage may be considered if ingestion was recent. Hemodialysis is not effective for removal due to high protein binding.

Storage

Store at room temperature (15–30°C or 59–86°F) in a tightly closed container, protected from light and moisture. Keep out of reach of children. Do not use after the expiration date.

Disclaimer

This information is for educational purposes and does not replace professional medical advice, diagnosis, or treatment. Always consult a healthcare provider for personalized recommendations and before starting any new medication. Do not discontinue prescribed therapy without consulting your physician.

Reviews

“Tetracycline has been a cornerstone in my dermatology practice for years, especially for persistent inflammatory acne. Patients show significant improvement within weeks, though gastrointestinal side effects require management.” — Dr. Elena Moss, Dermatologist
“As an infectious disease specialist, I value tetracycline for its role in treating rickettsial infections and community-acquired pneumonia. Its cost-effectiveness makes it accessible in various healthcare settings.” — Dr. Robert Kline, MD
“Used tetracycline for my bronchitis—effective but upset my stomach. Taking it with plenty of water and avoiding dairy helped.” — Patient, 34
“Prescribed for acne. Noticeable reduction in inflammation and breakouts after a month. Sun sensitivity was an issue, so sunscreen became essential.” — Patient, 19