Tetracycline is a broad‑spectrum antibiotic that inhibits bacterial protein synthesis by binding to the 30S ribosomal subunit. First isolated in the 1940s, it remains on the WHO Essential Medicines List and is frequently prescribed for skin infections such as acne, impetigo, and cellulitis.
When a rash, boil, or pustule won’t clear up, many clinicians reach for tetracycline because it’s cheap, oral, and effective against a wide range of Gram‑positive and Gram‑negative bacteria. Yet the drug isn’t a magic bullet - proper dosing, awareness of side effects, and vigilance about resistance are essential for success.
How Tetracycline Works on the Skin
Once absorbed, tetracycline circulates into the dermis and epidermis, where it blocks the addition of new amino acids to bacterial proteins. This bacteriostatic action stalls the growth of organisms like Staphylococcus aureus, a common cause of cellulitis and impetigo. For acne, the drug also reduces inflammation by dampening the activity of neutrophils and decreasing the production of inflammatory cytokines.
When to Use Tetracycline for Skin Infections
Typical indications include:
- Uncomplicated acne vulgaris (moderate‑to‑severe inflammatory lesions)
- Impetigo caused by Staphylococcus aureus or Streptococcus pyogenes
- Early‑stage cellulitis when oral therapy is appropriate
- Folliculitis and other superficial follicular infections
For deep tissue infections, hospitals often prefer intravenous agents, but for most outpatient skin conditions, oral tetracycline is a first‑line option.
Dosage and Administration
Adults usually receive 250-500mg every 6-12hours, depending on severity. Children under 8years are generally excluded because of permanent tooth discoloration. A typical regimen looks like this:
- Take the first dose with a full glass of water.
- Repeat every 8hours for 7-14days.
- Avoid dairy, calcium supplements, and antacids within two hours of dosing-these bind the drug and cut absorption by up to 50%.
Therapeutic drug monitoring isn’t routine, but for patients with renal failure, the dose may be reduced to 250mg twice daily.
Safety Profile: Side Effects and Contra‑indications
Most people tolerate tetracycline well, but be on the lookout for:
- Gastrointestinal upset (nausea, vomiting, diarrhea)
- Photosensitivity - patients should use sunscreen and wear protective clothing outdoors.
- Tooth discoloration and enamel hypoplasia in children < 8years.
- Rare hepatotoxicity and intracranial hypertension (especially in women of child‑bearing age).
Contra‑indications include pregnancy (Category D), known hypersensitivity, and severe liver disease. If a patient reports persistent nausea or a skin rash, switch to an alternative like Doxycycline or Clindamycin.
Resistance: Why It Matters
Over the past two decades, tetracycline‑resistant strains of MRSA (methicillin‑resistant Staphylococcus aureus) have risen, especially in community settings. Resistance mechanisms include efflux pumps and ribosomal protection proteins. To preserve efficacy:
- Reserve tetracycline for confirmed susceptible organisms.
- Complete the full course - stopping early fuels resistance.
- Combine with topical agents (e.g., benzoyl peroxide for acne) to reduce bacterial load.
National guidelines, such as those from the FDA, advise culture‑guided therapy when possible.
Comparison with Other Oral Antibiotics
| Attribute | Tetracycline | Doxycycline | Clindamycin |
|---|---|---|---|
| Spectrum | Broad (Gram‑+, Gram‑‑, atypicals) | Broad, stronger against anaerobes | Excellent for Gram‑+ anaerobes, MRSA |
| Typical oral dose | 250-500mg q6‑12h | 100mg q12h | 300mg q6h |
| Common side effects | Photosensitivity, GI upset | Less photosensitivity, GI upset | Diarrhea, C.difficile risk |
| Pregnancy safety | Category D (avoid) | Category B (more acceptable) | Category B |
| Resistance concern | Increasing tetracycline‑resistance | Lower resistance rates | High MRSA resistance in some regions |
For most healthy adults with mild‑to‑moderate acne, tetracycline skin infection therapy is cost‑effective. In pregnant patients or those with severe photosensitivity, doxycycline may be a safer choice, while clindamycin shines against resistant Gram‑positive organisms.
Practical Tips for Clinicians and Patients
- Check susceptibility. Lab tests confirming Staphylococcus aureus sensitivity guide whether tetracycline will work.
- Educate on food interactions. Dairy and calcium supplements are the biggest absorptive roadblocks.
- Monitor liver function. Baseline AST/ALT in patients with known hepatic disease.
- Use sunscreen. Recommend SPF30+ and protective clothing for patients on therapy.
- Document outcome. Record lesion size reduction and any adverse events at day7 and day14.
Following these steps keeps the treatment safe, effective, and minimizes the chance of developing resistant strains.
Related Concepts and Next Steps
Understanding tetracycline fits into a broader picture of antibiotic stewardship. Good stewardship means prescribing the narrowest effective agent, using the shortest effective duration, and educating patients about adherence. Readers interested in the big picture may explore topics such as:
- Mechanisms of bacterial resistance (efflux pumps, ribosomal protection)
- Topical versus oral therapy for acne
- Guidelines from the WHO Essential Medicines List on skin infection management
- Emerging oral agents like omadacycline
Each of these areas builds on the foundation covered here and can help clinicians stay ahead of evolving resistance patterns.
Frequently Asked Questions
Can I take tetracycline if I’m pregnant?
No. Tetracycline is classified as Pregnancy Category D because it can cause tooth discoloration and inhibit bone growth in the fetus. Safer alternatives like doxycycline or clindamycin are preferred.
How long should I stay on tetracycline for acne?
Typical courses last 8‑12weeks. Some dermatologists extend therapy up to 6months if lesions keep improving, but treatment should be reassessed after the initial 2‑month period.
Why does tetracycline cause photosensitivity?
The drug accumulates in the skin and, when exposed to UV light, generates reactive oxygen species that damage skin cells. This reaction explains the heightened sunburn risk.
Is it safe to take tetracycline with calcium supplements?
No. Calcium chelates tetracycline, dropping its absorption by up to 50%. Space the supplement at least two hours before or after the antibiotic.
What should I do if I develop a rash while on tetracycline?
Stop the medication immediately and contact your healthcare provider. A rash could signal an allergic reaction or a severe side effect like Stevens‑Johnson syndrome, which requires urgent evaluation.
How does tetracycline compare to doxycycline for treating skin infections?
Both belong to the tetracycline class, but doxycycline has a longer half‑life, allowing twice‑daily dosing, and causes less photosensitivity. Doxycycline also has a slightly better resistance profile. However, both are effective; choice often hinges on patient tolerance and cost.
Can children under 8 years take tetracycline?
No. The drug can permanently stain developing teeth and affect bone growth. For pediatric skin infections, other antibiotics like amoxicillin or cephalexin are recommended.