So, this medicine is basically an antibiotic. That means it’s made to fight bacterial infections, not things like colds or flu, because those are caused by viruses. A lot of people take antibiotics thinking they’ll fix everything, but nope — this one works only on certain bacteria.
The main thing inside this medicine is called lymecycline. It’s part of a group of antibiotics known as tetracyclines. You don’t need to remember the name, just know that it’s a type of antibiotic that doctors like to use for specific infections.
You’ll mainly see it being used for things like:
- Acne that just won’t go away, even after trying creams or face washes
- Chest and throat infections
- Some sexually transmitted infections (STIs)
- Eye infections, and a bunch of other bacterial problems that doctors diagnose
Now, here’s something important: this medicine is not the kind you just pick up at the pharmacy on your own. It’s listed as Schedule 4 (S4), which basically means you must have a prescription from a doctor. It’s strong, it needs to be used the right way, and it’s not safe to take it just because someone else used it.
What it is and what it is used for
What it is
Tetralysal contains lymecycline, an antibiotic in the tetracycline class (ATC code: J01AA04). It is supplied as hard gelatin capsules. Each capsule contains lymecycline equivalent to 150 mg or 300 mg tetracycline base.
What it is used for
- Upper and lower respiratory tract infections:
Sinusitis, pharyngitis, Mycoplasma pneumoniae infection, psittacosis, and chronic bronchitis. - Genito-urinary tract infections:
Non-specific urethritis (only if the strain is sensitive), lymphogranuloma venereum, chancroid and granuloma inguinale, gonococcal salpingitis, epididymitis, acute epididymo-orchitis, endocervical infections, syphilis and gonorrhoea (in cases of penicillin allergy). - Soft tissue:
Acne. - Ophthalmic infections:
Trachoma and inclusion conjunctivitis. - Intestinal infections:
Cholera, Whipple’s disease and tropical sprue. - Miscellaneous infections:
Rickettsial infections, brucellosis, tularemia, actinomycosis, Lyme disease, yaws, relapsing fever, and leptospirosis during the early infective phase.
Note: Indications are limited to infections caused by susceptible organisms. Prescribers should follow antibiotic stewardship principles.
How it works
Lymecycline slows or stops the growth of certain bacteria. In scientific terms, it binds to the 30S ribosomal subunit inside bacterial cells, interfering with the way bacteria make proteins. Without these proteins, bacteria cannot multiply effectively, so the infection can resolve as the body’s defences do their job.
Who should NOT use this medicine
Do not use Tetralysal if:
- You are allergic to lymecycline, any tetracycline, or any of the capsule ingredients (see “What the medicine contains”).
- You have impaired renal (kidney) function.
- You are younger than 12 years (risk of permanent tooth discolouration and enamel hypoplasia).
- You have systemic lupus erythematosus (SLE).
- You are pregnant or breastfeeding.
- You are using oral retinoids (for example, isotretinoin) at the same time.
Warnings and precautions (Read before use)
Read all points carefully and discuss them with a healthcare professional if unsure.
General cautions
- Kidney or liver problems: Use with care if you have renal or hepatic impairment.
- Elderly or frail: More susceptible to liver-related side effects and to the antianabolic (tissue-breakdown) effects of tetracyclines.
- Hepatotoxicity: Overdosage can cause liver toxicity. Do not combine with other hepatotoxic medicines.
- Antibiotic resistance: Prolonged or inappropriate use of broad-spectrum antibiotics can lead to resistant bacteria and superinfection. Take exactly as prescribed and for the full course.
Oesophageal irritation and ulceration
Solid tetracycline capsules can irritate the oesophagus (food pipe) and may cause ulceration.
- Always swallow capsules with plenty of water.
- Take 1 hour before or 2 hours after meals.
- Do not allow the capsule to lodge in your throat.
Photosensitivity (sun sensitivity)
Tetralysal can make your skin more sensitive to light:
- Avoid direct sunlight and ultraviolet (UV) light (including tanning beds) during treatment.
- Stop treatment and contact a healthcare professional if you develop redness or a rash after sun exposure.
Expired medication
Do not use expired tetracyclines. The use of expired products in this class has been associated with a Fanconi-type syndrome (a form of renal tubular acidosis) with symptoms such as urinating a lot, excessive thirst, nausea, vomiting, and various electrolyte abnormalities. These symptoms are reversible once the medicine is stopped.
Conditions that may worsen
- Systemic lupus erythematosus (SLE): May exacerbate SLE.
- Myasthenia gravis: Symptoms may be aggravated.
Paediatric considerations
- Under 12 years: Contraindicated due to risks to teeth and enamel.
- Raised intracranial pressure: Can occur, particularly in infants, and especially if vitamin A or retinoids are taken at the same time.
Effects on ability to drive and use machines
Tetralysal is not known to affect your ability to drive or operate machinery.
Pregnancy, planning pregnancy, and breastfeeding
- Pregnancy: Do not use. Lymecycline crosses the placenta and is deposited in foetal bones and teeth. Pregnant women are particularly susceptible to severe tetracycline-induced liver damage.
- Breastfeeding: Do not use. Lymecycline is excreted in breast milk.
- Fertility: Not specified .
If you are planning a pregnancy or become pregnant while taking Tetralysal, speak to your doctor immediately.
Interactions
Only the interactions listed in the source are included below. Ask a pharmacist or doctor to review all your medicines and supplements before starting Tetralysal.
Medicines and substances that reduce absorption of lymecycline
These can bind to the antibiotic in the gut and lower its effect. Do not take within 2 hours before or after Tetralysal.
- Antacids and mineral preparations: sodium bicarbonate; iron; magnesium, aluminium and calcium hydroxides/oxides/salts.
- Other gut-binding agents: cholestyramine, bismuth chelate, sucralfate, quinapril.
- Milk: Do not take with milk.
Medicines that change the way Tetralysal is processed
- Liver enzyme inducers (may shorten the half-life of tetracycline): barbiturates, carbamazepine, phenytoin.
- Timing rule: The products above should not be taken within two hours before or after Tetralysal.
Medicines that should be avoided with Tetralysal
- Oral retinoids and vitamin A (above 10 000 IU/day): increased risk of benign intracranial hypertension.
- Diuretics: Avoid concomitant use.
- Penicillins and other beta-lactam antibiotics: Do not combine—antagonism may occur.
- Methoxyflurane (anaesthetic): Concomitant use has been associated with fatal renal toxicity.
Medicines that may need dose adjustments or caution
- Anticoagulants: Doses may need to be reduced when used together.
- Lithium: Concomitant use may increase serum lithium levels.
- Oral contraceptives: Tetracyclines may diminish effectiveness of oral contraceptives.
Paediatric note: Interaction studies have been performed only in adults.
How to take (Step-by-step)
- Check your prescription to confirm your dose and duration.
- Timing with food: Take capsules on an empty stomach—1 hour before or 2 hours after a meal.
- Swallow whole with plenty of water to prevent the capsule from sticking in the oesophagus.
- Spacing from other products:
- Avoid milk, antacids, iron, magnesium/aluminium/calcium products, cholestyramine, bismuth chelate, sucralfate and quinapril for 2 hours before and after each dose.
- Sun protection: Avoid direct sun and UV exposure during treatment.
- Do not use if expired.
Adult doses
- Acne: 300 mg once daily. Usual duration: 12 weeks.
- Infections other than acne: 300 mg every 12 hours (dose depends on infection severity—follow your doctor’s instructions).
Elderly
- No specific dose adjustment is required beyond standard adult dosing (as for other tetracyclines).
Paediatric use
- Under 12 years: Do not use (contraindicated).
- Maximum daily dose for children (per source):50 mg/kg/day.
- Important: Although a paediatric maximum is stated in the source, safety and efficacy are not established under 12 years, and use in this age group is contraindicated.
Missed dose
- Not specified in the source. Speak to your doctor or pharmacist for advice on what to do if you miss a dose.
Overdose
- In overdose, side effects can appear or become more severe. If unusual symptoms occur, stop the medicine and seek medical help. Treatment is symptomatic and supportive.
Practical adherence tips
- Take at the same time(s) each day.
- Use a reminder to keep the 2-hour gap from milk, antacids, or mineral products.
- Keep sun protection habits front-of-mind while on treatment.
- Never take expired capsules.
Dosing table
| Population / Indication | Dose | Frequency | Usual Duration | Key Notes |
|---|---|---|---|---|
| Adults – Acne | 300 mg | Once daily | 12 weeks | Take on an empty stomach with plenty of water. |
| Adults – Other infections | 300 mg | Every 12 hours | As directed (depends on severity) | Follow prescriber’s instructions; maintain 2-hour gap from milk/antacids/mineral products. |
| Elderly | As for adults | As for adults | As directed | No specific adjustment required (as with other tetracyclines). |
| Children <12 years | — | — | — | Contraindicated. Safety and efficacy not established. |
| Maximum daily dose – Adults | Up to 3 g/day | — | — | Do not exceed maximum. |
| Maximum daily dose – Children | Up to 50 mg/kg/day | — | — | Under 12 years: do not use despite this general maximum being listed in source. |
Possible side effects
The following side effects were reported in the source document. The most frequently noted were nausea, abdominal pain, diarrhoea, and headache. The most serious events reported included Stevens-Johnson syndrome, anaphylactic reaction, angioneurotic oedema, and intracranial hypertension.
Warning: If you develop signs of a severe allergic reaction (such as swelling of the face/lips/tongue or difficulty breathing), severe skin rash, yellowing of the skin/eyes, severe/persistent headache with visual disturbances, or severe diarrhoea, stop Tetralysal and seek urgent medical help.
Common (≥1/100 and <1/10)
- Gastrointestinal: Nausea, abdominal pain, diarrhoea.
- Nervous system: Headache.
Less common / Frequency not known
- Gastrointestinal: Epigastric pain, glossitis (inflamed tongue), vomiting, enterocolitis.
- General: Fever (pyrexia).
- Liver and bile: Jaundice, hepatitis.
- Immune system / Allergy: Hypersensitivity, urticaria (hives), angioneurotic oedema (swelling).
- Investigations: Raised transaminases, alkaline phosphatase, bilirubin.
- Nervous system: Dizziness, intracranial hypertension.
- Skin: Erythematous rash, photosensitivity, pruritus (itch), Stevens-Johnson syndrome.
- Psychiatric: Depression, nightmares.
- Blood/lymph: Haemolytic anaemia, eosinophilia, neutropenia, thrombocytopenia.
Additional reactions
- Overgrowth of non-susceptible organisms:
- Candida albicans in the mouth (soreness/redness/thrush), possibly extending into the trachea/bronchi.
- Candida in the bowel (itch around the anus—pruritis ani—and vulvovaginitis).
- Overgrowth of resistant coliform organisms (e.g., Pseudomonas, Proteus) causing diarrhoea.
- Clostridium difficile-associated colitis may occur.
- Resistant staphylococci may cause fulminating enteritis.
- Allergic/hypersensitivity patterns:
Maculopapular rashes, exfoliative dermatitis, exacerbation of SLE, pericarditis, and Henoch-Schönlein purpura (anaphylactoid purpura). Photosensitivity can also affect skin and nails, including onycholysis (nail lifting) and nail discolouration. - Other notes from the source:
- In patients with renal disease receiving high doses: increased severity of uraemia and hepatotoxicity.
- Vitamin deficiencies may occur with prolonged administration.
- A Jarisch-Herxheimer-like reaction has been reported in relapsing fever treated with tetracycline (a short-term reaction due to bacterial die-off).
- In the elderly, a negative nitrogen balance may be induced.
What to do: Mild effects (such as nausea) often improve, but if symptoms are troublesome, persistent, or severe, contact a healthcare professional. For any serious symptoms (see Warning above), seek urgent help.
Storage and disposal
- Storage temperature: Keep in a cool, dry place at or below 25 °C.
- Children: Keep out of reach of children.
- Shelf life: 2 years.
- Disposal: Not specified in the source. Ask your pharmacist how to dispose of medicines you no longer use.
- Expired capsules: Do not use. See Expired medication under Warnings.
What the medicine contains
Active ingredient
- Tetralysal 150 mg: Lymecycline equivalent to 150 mg tetracycline base per capsule.
- Tetralysal 300 mg: Lymecycline equivalent to 300 mg tetracycline base per capsule.
Excipients (capsule contents and shell)
- Tetralysal 150 mg (capsule content):Magnesium stearate, colloidal hydrated silica, maize starch, lactose monohydrate.
- Capsule shell: Gelatin, erythrosin (E127), quinoline yellow (E104), titanium dioxide (E171).
- Tetralysal 300 mg (capsule content):Magnesium stearate, colloidal hydrated silica.
- Capsule shell: Gelatin, erythrosin (E127), indigo carmine (E132), quinoline yellow (E104), titanium dioxide (E171).
Note: The 150 mg capsule contains lactose (lactose monohydrate).
Pack information and appearance
- Pharmaceutical form: Hard gelatin capsules containing a granular yellow powder.
- Tetralysal 150 mg: Orange cap and yellow body.
- Tetralysal 300 mg: Red cap and yellow body.
- Pack size: Blister packs of 28 capsules, packed in a carton.
FAQs
1) Can I take Tetralysal with milk or antacids?
No. Milk and certain antacids/mineral products reduce absorption. Keep a 2-hour gap before and after your Tetralysal dose.
2) Can I go out in the sun while taking Tetralysal?
Avoid direct sunlight and UV exposure. Tetralysal may cause photosensitivity. Stop treatment and seek advice if you develop redness or a rash after sun exposure.
3) Can I take Tetralysal if I’m pregnant or breastfeeding?
No. Do not use during pregnancy or breastfeeding.
4) Is Tetralysal suitable for children?
Not for children under 12 years. It is contraindicated due to risks to teeth and enamel. Safety and efficacy are not established under 12 years.
5) Does Tetralysal affect the pill (oral contraceptives)?
Yes, it may. Tetracyclines may diminish the effectiveness of oral contraceptives.
6) Can I use Tetralysal with retinoids or vitamin A?
Avoid. Oral retinoids and vitamin A (>10 000 IU/day) should not be taken with Tetralysal due to the risk of benign intracranial hypertension.
7) Will Tetralysal make me drowsy or affect driving?
It is not known to affect the ability to drive or use machines.
8) What should I do with expired Tetralysal capsules?
Do not use them. Expired tetracyclines have been associated with a Fanconi-type syndrome. Ask a pharmacist about safe disposal.
9) How long is the usual course for acne?
The usual duration reported in the source is 12 weeks at 300 mg once daily.
10) How should I time my doses with meals?
Take on an empty stomach—1 hour before or 2 hours after food—and swallow with plenty of water.
Manish Sharma is a Master’s graduate in Pharmaceutical Chemistry and a registered pharmacist with a passion for simplifying medical knowledge for everyday readers. Through his platform, he provides clear, easy-to-understand information about medicines — including their correct usage, benefits, and safety tips — while also addressing common myths surrounding them.
Alongside modern medicine, Manish also explores natural and herbal remedies, encouraging a balanced and healthy lifestyle. His mission is to empower people with reliable health information, helping them make informed decisions and live healthier, happier lives.
