Doxycycline is a type of antibiotic called a tetracycline and is used to treat infections caused by bacteria.
Doxycycline is also active against the parasite that causes malaria and is sometimes used to treat malaria.
However doxycycline is most commonly used for preventing malaria in areas of the world where there is a high risk of falciparum malaria being resistant to chloroquine.
It is thought to work by inhibiting the synthesis of proteins that are involved in the reproduction of the infecting organism.
It is important to check with your pharmacist which medicines are currently recommended to prevent malaria in the country to which you are travelling.
The adult dose for prevention of malaria is 100mg once a day starting two days before departure to an area of malaria risk. It should be continued throughout exposure and for 4 weeks afterwards. It is very important to complete the course.
Take your tablets with food and at the same time each day. If you miss a dose, take one as soon as you remember then carry on as before (you may have to get more tablets).
Never take two doses at the same time.
Heartburn is common if capsules release their contents into the gullet so they should be taken with a full glass of water and preferably while standing upright and not just before going to lie down in bed.
No guidance is given by the manufacturers on prolonged usage for malaria prevention but doxycycline has been used for periods of up to 2 years for acne treatment without an increased risk of side effects.
Do not take indigestion remedies or medicines containing aluminium, calcium, iron, magnesium or zinc at the same time of day as doxycycline, because these can reduce the absorption from the gut.
Medicines and their possible side effects can affect individual people in different ways. Just because a side effect is stated here does not mean that all people using this medicine will experience that or any side effect. The following are some of the side effects that are known to be associated with doxycycline:
- Disturbances of the gut, such as nausea, vomiting, diarrhoea, indigestion or abdominal pain.
- Difficulty or pain when swallowing (dysphagia).
- Inflammation of the food pipe (oesophagitis).
- Loss of appetite.
- Sensation of ringing or other noise in the ears (tinnitus).
- Increased sensitivity of the skin to UV light (photosensitivity).
- Aching muscles or joints.
- Disturbances in the normal numbers of blood cells in the blood (rare). Consult your doctor if you experience unusual bruising or bleeding, tiredness, sore throat, fever or other signs of infection while taking this medicine, as these could be symptoms of problems with your blood cells.
- Liver problems, including jaundice, hepatitis or liver failure (rare).
- Inflammation of the pancreas (pancreatitis - rare).
- Skin rashes (rare).
- Mild increase in pressure within the skull (benign intracranial hypertension). This is rare. However, you should stop taking this medicine and consult your doctor if you experience a severe persistent headache or changes in your vision while taking this medicine, e.g. blurred or double vision or loss of vision, as these could be symptoms of this condition.
- Rarely, severe allergic reactions, such as swelling of the lips, throat and tongue (angioedema), severe skin rashes or anaphylactic shock.
The side effects listed above may not include all of the side effects reported by the medicine's manufacturer. For more information about any other possible risks associated with doxycycline, please read the information provided with the medicine or consult your doctor or pharmacist.
In some people this medicine can cause the skin to become more sensitive to sunlight and UV light, causing an exaggerated sunburn reaction. For this reason you should avoid excessive exposure to strong sunlight, and avoid using sunbeds and sunlamps while you are taking this medicine.
Occasionally this antibiotic may upset the natural balance of micro-organisms in the body, allowing those that are not susceptible to doxycycline to overgrow and cause infection. This may happen with yeasts such as Candida, resulting in thrush infections. If you think you have developed a new infection while taking this medicine, you should consult your doctor.
Broad-spectrum antibiotics like doxycycline can sometimes cause inflammation of the bowel (colitis). For this reason, if you get diarrhoea that becomes severe or persistent or contains blood or mucus, either during or after taking this medicine, you should consult a doctor immediately.
Doxycycline should be used with caution in:
- Decreased kidney function.
- Decreased liver function.
- People taking medicines with potential to cause adverse effects on the liver.
- A condition called systemic lupus erythematosus, in which there is long-term inflammation of skin and some internal organs.
- Abnormal muscle weakness (myasthenia gravis).
Doxycycline should NOT be used in:
- Children under 12 years of age.
- Allergy to other tetracycline-type antibiotics, e.g. tetracycline, minocycline.
- Hereditary blood disorders called acute porphyrias.
This medicine should not be used if you are allergic to one or any of its ingredients. Please inform your doctor or pharmacist if you have previously experienced such an allergy. If you feel you have experienced an allergic reaction, stop using doxycycline and inform your doctor or pharmacist immediately.
The patient information leaflet (PIL) is a leaflet containing specific information about medical conditions, doses and side effects. You can download a copy of the PIL here:
Patient Info Leaflet