Doxytet contains doxycycline 100 mg, a prescription antibiotic from the tetracycline family. It is used for chest infections, acne, sexually transmitted infections, tick bite fever and as malaria prevention. “Green” refers to the capsule colour, not a different medicine.
What is Doxytet Green?
Doxytet is registered in South Africa as a Schedule 4 capsule containing doxycycline hydrochloride 100 mg — prescription-only.
“Green” describes the capsule, not the contents. Manufacturers use colour to distinguish products and packs, and people naturally describe a capsule by how it looks. If your pack says Doxytet, the medicine inside is doxycycline 100 mg.
Doxycycline is a tetracycline antibiotic. It binds to the bacterial ribosome — the machinery that assembles proteins — and blocks it, so the bacterium cannot make the proteins it needs to grow and divide. Human ribosomes are structured differently, which is what makes the effect selective.
It is bacteriostatic rather than bactericidal: it stops bacteria multiplying and leaves the immune system to clear them. That is one reason completing the course matters.
Doxycycline is unusually broad in what it covers, including organisms many antibiotics miss — Chlamydia, Mycoplasma, Rickettsia (the cause of tick bite fever), Borrelia and some malaria parasites. That breadth explains its unusually varied list of uses.
It also has an anti-inflammatory effect at low doses, independent of killing bacteria, which is part of why it works in acne and rosacea.
What is Doxytet Green commonly used for?
A doctor may prescribe it for:
- Chest infections, including some pneumonia and infective exacerbations of COPD.
- Acne and rosacea, usually as a longer course at a lower dose.
- Sexually transmitted infections, particularly chlamydia — a first-line treatment.
- Pelvic inflammatory disease, with other antibiotics.
- Tick bite fever, common in South Africa and treated with doxycycline as first choice.
- Malaria prevention, for travellers to malaria areas, taken daily.
- Skin and soft-tissue infections.
- Some urinary and prostate infections.
- Sinusitis and dental infections, in some cases.
- Leptospirosis, brucellosis and other less common infections.
It has no effect on viruses. Colds, flu, most sore throats and most coughs are viral, and an antibiotic will not shorten them.
For malaria prevention, timing is specific: doxycycline is usually started before travel, taken every day during the stay, and continued for four weeks after leaving the area. That final four weeks is not optional — stopping on the way home is a common and dangerous mistake, because it is the period when the parasite would otherwise emerge from the liver.
How Doxytet Green fits into this medicine category
| Group | Examples | Typical role |
|---|---|---|
| Tetracyclines | Doxycycline (Doxytet) | Chest, skin, STIs, tick bite fever, malaria prophylaxis |
| Penicillins | Amoxicillin, flucloxacillin | Common first-line choices |
| Cephalosporins | Cefalexin | Skin, throat, urinary infections |
| Macrolides | Azithromycin | Chest infections, penicillin allergy |
| Fluoroquinolones | Ciprofloxacin | Urinary, gut and bone infections; reserved |
| Nitroimidazoles | Metronidazole | Anaerobic and some parasitic infections |
See the antibiotics and antimicrobials hub.
What to check before using Doxytet Green
Take it with a full glass of water, sitting or standing upright, and do not lie down for at least 30 minutes afterwards. This is the most important practical instruction. Doxycycline capsules can lodge in the oesophagus and cause a painful ulcer there — a well-recognised problem, and entirely avoidable by staying upright with plenty of water. Taking it at bedtime without doing this is the classic scenario.
Separate it from calcium, magnesium, iron, zinc and antacids by two to three hours. These bind doxycycline in the gut and stop it being absorbed — including milk and dairy products, calcium supplements and multivitamins. This is a common reason treatment fails.
Use sun protection. Doxycycline commonly causes photosensitivity, and severe sunburn from ordinary sun exposure is a frequent complaint — genuinely relevant in South Africa. Cover up and use sunscreen throughout the course.
Complete the full course.
Tell your doctor or pharmacist if you:
- Are pregnant, planning pregnancy or breastfeeding. Doxycycline is avoided in pregnancy, as tetracyclines affect developing bones and teeth.
- Are giving it to a child under 8, where it can permanently stain developing teeth and is generally avoided.
- Have liver or kidney disease.
- Have myasthenia gravis, or lupus.
- Have difficulty swallowing, or a history of oesophageal problems.
- Take warfarin, whose effect may increase.
- Take antacids, iron or mineral supplements.
- Take carbamazepine, phenytoin, phenobarbital or rifampicin, which reduce doxycycline levels.
- Take isotretinoin — this combination should be avoided.
- Use the combined oral contraceptive pill. Antibiotics do not generally reduce its effectiveness, but severe vomiting or diarrhoea can.
Possible cautions and when to ask a pharmacist or doctor
Common effects are nausea, abdominal discomfort, diarrhoea, loss of appetite, and increased sun sensitivity. Taking it with food reduces stomach upset — just not with dairy.
Stop and seek medical attention if you develop:
- Pain or difficulty on swallowing, or pain behind the breastbone — possible oesophageal ulceration.
- Severe sunburn, or a rash on sun-exposed skin.
- Swelling of the face, lips or tongue, or difficulty breathing.
- A widespread rash, blistering or peeling skin, or sores in the mouth or eyes.
- Severe, watery or bloody diarrhoea, during or after the course — possible C. difficile infection, where anti-diarrhoeal medicines should not be used.
- Yellowing of the eyes or skin, or dark urine.
- Severe headache with visual disturbance, which can rarely indicate raised pressure around the brain.
- Vaginal or oral thrush, which is common and treatable.
- Muscle weakness, if you have myasthenia gravis.
Contact your doctor if you are no better after a few days, or if symptoms worsen at any point.
For acne, expect a slow response — improvement usually takes six to eight weeks, and courses often run for months under supervision. Judging it after two weeks is judging it too early.
For tick bite fever, seek medical attention promptly if you develop fever, headache and a rash after a tick bite, particularly with a dark scab at the bite site.
Related medicine guides
- Browse Antibiotics, Antifungals & Antimicrobials guides
- Read: Azrotrin used for
- Read: Metronidazole used for
Frequently asked questions
What are Doxytet green capsules used for? Bacterial infections including chest infections, acne, chlamydia and other STIs, tick bite fever, and as malaria prevention. Each capsule contains doxycycline 100 mg.
Does the green colour mean something different? No. It is the capsule colour. The medicine inside is doxycycline 100 mg.
Why must I stay upright after taking it? Doxycycline capsules can lodge in the oesophagus and cause a painful ulcer. Take it with a full glass of water and stay upright for at least 30 minutes.
Can I take it with milk? No. Calcium binds doxycycline and stops it being absorbed. Separate dairy, antacids and mineral supplements by two to three hours.
Why does it make me sunburn easily? Doxycycline causes photosensitivity. Use sunscreen and cover up throughout the course.
Can I take it in pregnancy? No. It is avoided in pregnancy and in children under 8, as tetracyclines affect developing bones and teeth.
How long until my acne improves? Usually six to eight weeks. Courses often run for months under medical supervision.
When do I stop taking it for malaria prevention? Four weeks after leaving the malaria area. Stopping earlier is a common and dangerous mistake.