Doxytet contains doxycycline 100 mg, a tetracycline antibiotic. It is used for chest and sinus infections, acne, some sexually transmitted infections, tick bite fever and as malaria prevention. It must be taken with plenty of water and while sitting or standing upright, and it makes skin burn more easily in the sun.
What is Doxytet?
Doxytet contains doxycycline 100 mg in capsule form, supplied in South Africa by Shanur Healthcare.
Doxycycline is a tetracycline antibiotic. It works by blocking bacterial ribosomes — the machinery bacteria use to build proteins. Without new proteins the bacterium cannot grow or divide. Human ribosomes are structured differently, which is why the medicine affects bacteria and not you.
It is described as bacteriostatic rather than bactericidal: it stops bacteria multiplying and leaves your immune system to clear them, rather than killing them outright. That is a normal and effective way for an antibiotic to work, and it is part of why finishing the course matters.
Doxycycline is well absorbed by mouth and reaches tissues that some antibiotics do not, including the lungs, skin, prostate and eye. That broad tissue distribution explains its unusually wide range of uses.
It is a Schedule 4 medicine in South Africa, dispensed as Doxytet, Cyclidox, Doximal and plain doxycycline.
What is Doxytet commonly used for?
Doxycycline is prescribed across a notably wide range:
- Chest infections, including atypical pneumonia and exacerbations of chronic bronchitis.
- Sinus infections.
- Acne, in longer low-dose courses, where it acts on both bacteria and inflammation.
- Rosacea.
- Sexually transmitted infections, particularly chlamydia, where it is a first-line treatment.
- Pelvic inflammatory disease, as part of a combination.
- Tick bite fever, which matters in South Africa — doxycycline is the treatment of choice.
- Malaria prevention for travellers to risk areas, taken before, during and after travel.
- Skin and soft tissue infections.
- Some eye infections and dental infections.
Tick bite fever deserves particular mention here. It is common in parts of South Africa, and doxycycline is the standard treatment. If you have a fever after a tick bite, especially with a dark scab at the bite site and swollen glands, that warrants prompt medical attention rather than waiting.
As with every antibiotic: it does nothing for colds, flu or other viral illness.
How Doxytet fits into this medicine category
Doxytet belongs to the tetracyclines, and its range overlaps the other classes at several points:
- Penicillins — amoxicillin — chest, ear, throat, dental, skin. Usually first choice where suitable.
- Macrolides — azithromycin — chest and throat, some STIs; option in penicillin allergy.
- Quinolones — ciprofloxacin — urinary, gut, bone. Reserved.
- Tetracyclines — doxycycline — chest, skin, STIs, tick bite fever, malaria prevention.
- Nitroimidazoles — metronidazole — anaerobic and parasitic.
- Antifungals — fluconazole — fungal only.
Doxycycline is often chosen when a penicillin is unsuitable, when atypical organisms are likely, or for the specific indications above where it is simply the right drug. See the antibiotics, antifungals and antimicrobials hub.
What to check before using Doxytet
Take it with a full glass of water, and stay sitting or standing upright for at least 30 minutes afterwards. This is not a minor instruction. Doxycycline can cause irritation and ulceration of the oesophagus if a capsule lodges there, which is painful and takes time to heal. Do not take it lying down or immediately before bed.
Separate it from dairy, antacids and mineral supplements. Calcium, magnesium, aluminium, iron and zinc bind doxycycline in the gut and reduce absorption — meaning an undertreated infection. Ask your pharmacist how many hours to leave either side.
Tell your prescriber or pharmacist if:
- You are pregnant, planning pregnancy or breastfeeding. Tetracyclines are generally avoided in pregnancy and in young children because they affect developing teeth and bone.
- The medicine is for a child under about 8, where it is normally avoided for the same reason.
- You have liver disease.
- You take warfarin — doxycycline can increase its effect.
- You take isotretinoin for acne — the combination raises the risk of raised pressure in the skull.
- You have myasthenia gravis or lupus.
Follow the dispensing label. This page does not set doses.
Possible cautions and when to ask a pharmacist or doctor
Sun sensitivity is the effect people notice most. Doxycycline makes skin burn far more easily, sometimes after brief exposure. In South African conditions this matters — use sun protection, cover up, and be cautious about extended time outdoors during a course. An unexpectedly severe sunburn is the usual presentation.
Take it upright with water, as above. Report painful or difficult swallowing.
Expect possible nausea and digestive upset. Taking it with food reduces this, though food also slightly reduces absorption — your pharmacist can advise on the balance for your situation.
Thrush is common, as with most antibiotics, because the normal bacterial balance is disturbed.
Severe or persistent diarrhoea, particularly with fever or blood, needs medical attention rather than an over-the-counter anti-diarrhoeal.
Finish the course, and do not save leftovers or take someone else’s.
For malaria prevention, the course continues for a defined period after leaving the risk area. Stopping early leaves you unprotected during the period the parasite may still emerge.
Seek medical attention for painful swallowing or chest pain after taking a capsule, severe sunburn, a spreading or blistering rash, severe headache with visual changes, yellowing of the eyes or skin, or severe diarrhoea.
Related medicine guides
- Browse Antibiotics, Antifungals & Antimicrobials guides
- Read: Azrotrin used for
- Read: Metronidazole used for
Frequently asked questions
What is Doxytet 100 mg used for? Chest and sinus infections, acne, chlamydia and some other STIs, tick bite fever, and malaria prevention. It contains doxycycline.
Why must I stay upright after taking it? A capsule lodging in the oesophagus can cause irritation and ulceration. Take it with a full glass of water and remain sitting or standing for at least 30 minutes.
Why does it make me burn in the sun? Doxycycline increases skin sensitivity to ultraviolet light. Use sun protection throughout the course.
Can I take it with milk? Better not. Calcium binds doxycycline and reduces absorption, which can undertreat the infection. Ask your pharmacist how long to leave either side.
Is it safe in pregnancy? Tetracyclines are generally avoided in pregnancy and in young children because they affect developing teeth and bone. Tell your prescriber.
Is doxycycline used for tick bite fever? Yes — it is the treatment of choice. Fever after a tick bite warrants prompt medical attention.