Tetracycline (Tetracycline Hydrochloride): Comprehensive Patient Information
Basic Product Information
| International Nonproprietary Name (INN) | Tetracycline |
|---|---|
| Australia Brand Names | Achromycin, Tetralysal, Panmycin, Sumycin (availability subject to state/territory) |
| ATC Code | J01AA07 |
| Available Forms and Strengths | Capsules (250 mg, 500 mg); Tablets (250 mg, 500 mg); Oral suspension (rarely available) |
| Manufacturers | Phebra, Sigma Pharmaceuticals, Arrow Pharma, Alphapharm |
| Prescription Status | Prescription Only (Schedule 4: Prescription Medicine) |
Mechanism of Action
Tetracycline is an antibiotic in the tetracycline class. It works by blocking the bacteria's ability to make proteins, which stops them from growing and multiplying.
For Specialists: Tetracycline binds to the 30S ribosomal subunit, inhibiting aminoacyl-tRNA binding and thus protein synthesis within susceptible bacteria.
Pharmacokinetics Overview
- Absorption: Well absorbed orally (60–80%), but significantly reduced by calcium, magnesium, aluminium, and iron (e.g., dairy or antacids).
- Metabolism: Limited metabolism; mostly excreted unchanged.
- Elimination: Primarily via urine (renal excretion) and to some extent in bile and faeces.
- Duration of Action: Half-life of 6–11 hours; dosing usually every 6–12 hours.
Use in Everyday Life and Best Practices in Australia
Tetracycline is used for various bacterial infections including acne, respiratory tract infections, urinary tract infections, and some sexually transmitted infections (e.g., chlamydia). In Australia, you’ll receive a prescription from your GP, and the medicine is dispensed by community pharmacies.
- Typical adult dose: 250 mg–500 mg every 6–12 hours depending on the infection type and severity.
- How to take: Swallow capsules whole, with a glass of water. Remain upright for at least 30 minutes after the dose to reduce the risk of oesophageal irritation.
- Australian context: Typically prescribed after a doctor’s assessment of your infection and history, considering local guidelines (Therapeutic Guidelines: Antibiotic).
- Complete the full course of medicine even if symptoms improve to prevent antimicrobial resistance.
Morning vs Evening Dosing: What’s Best?
- Morning: Taking the first dose of the day in the morning promotes adherence, minimises forgetfulness, and can reduce stomach upset if taken with a light breakfast. Staying upright is easier in the day, lessening reflux risk.
- Evening: Nighttime doses can risk taking the medicine too close to bedtime (risking throat irritation/ulceration) if you lie down soon after.
- Consistency: Try to take your doses at the same times daily, spaced evenly. This helps maintain steady drug levels in your system, improving outcomes.
Taking Tetracycline with Food or on an Empty Stomach
- Best taken: On an empty stomach (at least 1 hour before or 2 hours after meals or dairy products).
- Why? Calcium, iron, magnesium, and some foodstuffs (especially dairy) significantly reduce absorption and effectiveness.
- Tip for Australians: If you usually eat a “hearty English breakfast”, wait or adjust dosing to avoid interference from milk, cheese, or high-calcium cereals.
- If you experience stomach upset: You may take with a small amount of food (non-dairy), but full effect may be reduced. Check with your pharmacist.
Interaction Warnings
| Item/Drug | Interaction Type | Advice |
|---|---|---|
| Dairy products (milk, cheese, yoghurt) | Reduces absorption | Avoid 2 hours before and after dose |
| Antacids (e.g. Mylanta, Gaviscon), iron, calcium, magnesium supplements | Reduces absorption | Avoid 2 hours before and after tetracycline |
| Alcohol | Increases risk of side effects | Limit alcohol during treatment |
| Warfarin | Increased bleeding risk | Monitor INR closely |
| Oral contraceptives | Effectiveness may be reduced | Use additional contraception |
| Retinoids (e.g. Roaccutane) | Increases risk of intracranial hypertension | Do not use together |
Indications for Use
| Official Indications | Off-Label Uses (specialist discretion) |
|---|---|
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Dosing According to Clinical Indications
| Condition | Adults | Children (≥8 years old) | Elderly |
|---|---|---|---|
| Acne vulgaris | 250–500 mg twice daily | 25–50 mg/kg/day in divided doses (max 1g/day) | Same as adults, consider renal function |
| Chlamydia (uncomplicated) | 500 mg every 6 hours for 7 days | See specialist; usually not standard in young children | Same as adults, monitor renal clearance |
| Respiratory tract infection | 250–500 mg every 6–12 hours | As above for age/weight | Adjust dose if kidney function impaired |
| Rickettsial infections | 500 mg every 6 hours | Not recommended for children <8 years | Cautious use—review comorbidities |
Note: Tetracyclines are usually avoided in children under 8 years due to risks of permanent tooth discolouration and effects on bone growth.
Safety Profile and Side Effects
| Common | Rare/Serious | Warnings |
|---|---|---|
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Guidelines for Proper Use (Australian Context)
- Always complete the prescribed course, even if you feel better.
- Take with a full glass of water and stay upright for 30 minutes after the dose.
- Avoid dairy, antacids, and iron around dose times.
- Report any rash, difficulty breathing, persistent headache, or visual changes to your doctor immediately.
- If you miss a dose, take it as soon as you remember—but skip it if it’s almost time for your next. Never double up.
- Discuss use with your pharmacist if you take supplements or have unusual dietary habits (vegan, high-dairy, etc.).
- Australian heat: If working outdoors, protect your skin and eyes as the medicine may increase sunburn risk.
Alternative Treatment Options (PBS-Listed)
- Doxycycline: More convenient dosing (once/twice daily), similar spectrum, often first-line for many infections (PBS reimbursed).
- Minocycline: Used particularly in acne, but higher risk of side effects (dizziness, pigmentation).
- Macrolides (e.g., azithromycin, erythromycin): Alternative for those intolerant of tetracyclines or in pregnancy.
- Penicillins/cephalosporins: For non-tetracycline-susceptible infections.
Each alternative has advantages and disadvantages in terms of dosing, side effects, resistance profiles, and suitability for special populations. Your healthcare provider will tailor the antibiotic choice to your specific case.
Legal, Registration, and Reimbursement Status in Australia
- Prescription Medicine: Schedule 4 (Rx only); not available over the counter.
- Regulated by: Therapeutic Goods Administration (TGA).
- PBS reimbursement: Some tetracycline brands/forms are listed for certain indications (e.g., acne, STIs). Doxycycline is more commonly covered.
- Not suitable for livestock use unless duly prescribed by a veterinarian as per Australian laws.
Latest Research and Clinical Guidance (2022–2025)
- Australian Therapeutic Guidelines (Antibiotic, 17th Edition): Recommends reserving tetracycline for specific indications due to rising resistance and more convenient alternatives (e.g., doxycycline).
- Use is generally limited to patients intolerant or allergic to other agents, or for infections with proven sensitivity to tetracycline.
- Emphasises prudent use to prevent antimicrobial resistance and preserve antibiotic effectiveness (TGA, PBS).
- Recent literature: Smith et al., Med J Aust 2023; Knight et al., J Infect Dis 2024 – supporting safety and efficacy for specific resistant infections and in acne management.
Availability and Delivery Information
Tetracycline is usually dispensed in 25, 50, and 100-capsule packs (250 mg or 500 mg). Prices vary based on pack size, brand, and concession status (e.g., indicative price for 50 x 500mg capsules: AUD $15–35 under general prescription; lower cost with Guardian/DVA/Health Care Card).
| Major City | Estimated Pharmacy Delivery Time |
|---|---|
| Sydney | Same day–2 days |
| Melbourne | Same day–2 days |
| Brisbane | 1–2 days |
| Perth | 2–4 days |
| Adelaide | 1–3 days |
| Regional/Rural | 2–7 days (dependent on AusPost/service) |
Frequently Asked Questions (FAQs)
1. Can I drink milk or eat cheese with my tetracycline?
No. Dairy products can interfere with the absorption of tetracycline, making it less effective. Wait at least 2 hours after or 1 hour before having dairy products.
2. What should I do if I miss a dose?
Take your missed dose as soon as you remember unless it’s nearly time for your next dose. Do not double up to make up for a missed dose.
3. Is it safe to take tetracycline during pregnancy or breastfeeding?
No. Tetracycline can harm unborn babies and should not be used during pregnancy or breastfeeding. If you are or may become pregnant, tell your doctor immediately.
4. Can children use tetracycline?
Tetracycline is not usually recommended for children under 8 years due to possible permanent tooth discoloration and effects on bone growth. Your doctor will choose another antibiotic for younger children.
5. How can I avoid stomach upset with tetracycline?
Take your tetracycline with a large glass of water and stay upright for at least 30 minutes. If necessary, you may take it with a small non-dairy snack.
