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Demeclocycline capsules

Demeclocycline is an antibiotic. Space out your doses during the day and make sure you continue to take the capsules until you finish the course prescribed.

The absorption of demeclocycline is adversely affected by food and dairy products. It is important that you take the capsules either one hour before a meal, or wait until two hours afterwards. Do not drink milk during the two hours before you take the capsules, or for two hours afterwards.

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About demeclocycline

Type of medicine

A tetracycline antibiotic

Used for

Bacterial infections;

Syndrome of inappropriate secretion of antidiuretic hormone (SIADH)

Available as

Capsules, tablets

Demeclocycline is an antibacterial medicine. This means that it stops infections caused by germs (bacteria). It is prescribed as a treatment for pneumonia, for infections resulting from some types of bites, for some sexually transmitted infections, and also for some rarer infections.

Demeclocycline is also prescribed for a condition called syndrome of inappropriate secretion of antidiuretic hormone (SIADH). This is a rare condition which leads to low levels of sodium in the blood.

Before taking demeclocycline

Some medicines are not suitable for people with certain conditions, and sometimes a medicine can only be used if extra care is taken. For these reasons, before you start taking demeclocycline it is important that your doctor knows:

  • If you are pregnant or breastfeeding. If so, you should not take demeclocycline.

  • If you are under 12 years of age. Demeclocycline should not be given to children.

  • If you have any problems with the way your liver works, or if you have any problems with the way your kidneys work.

  • If you have an inflammatory condition called systemic lupus erythematosus (also called lupus, or SLE), or if you have a condition causing muscle weakness, called myasthenia gravis. Demeclocycline can make these conditions worse.

  • If you have a rare inherited blood disorder called porphyria.

  • If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.

  • If you have ever had an allergic reaction to a medicine.

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How to take demeclocycline

  • Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about demeclocycline, and it will also provide you with a full list of the side-effects which you could experience from taking it.

  • Take demeclocycline exactly as your doctor tells you to. If you have an infection you will be asked to take either one (150 mg) capsule every six hours, or two capsules every twelve hours. If you are being treated for low sodium levels, you could be asked to take up to eight capsules a day in divided doses. Your doctor or pharmacist will tell you what dose is right for you, and this information will also be printed on the label of the pack to remind you about what was said to you.

  • Try to take your doses around the same times of day each day. This will help you remember to take them regularly. Space out your doses evenly throughout the day.

  • Take the capsules when your stomach is empty. This means taking your doses one hour before you eat food, or waiting until two hours after you have eaten. It is also important that you do not drink milk within two hours (either before or after) of taking demeclocycline. This is because both food and milk can reduce the amount of medicine absorbed by your body, making it less effective in fighting infection.

  • Swallow the capsules with a large drink of water. Do not open or chew the capsules. Try to avoid taking demeclocycline just before lying down or at bedtime.

  • If you forget to take a dose, take it as soon as you remember. Try to take the correct number of doses each day, but do not take two doses together to make up for a missed dose.

Getting the most from your treatment

  • If you are being treated for an infection, your course of treatment is likely to last for a week or so. It is important that you keep taking demeclocycline regularly until the course is finished (unless you are told to stop sooner by a doctor). If you are taking demeclocycline for low sodium levels, your treatment is likely to be long-term, so continue to take the capsules until you are advised otherwise.

  • If you buy any medicines, check with a pharmacist that they are suitable to take with demeclocycline, as a number of 'over-the-counter' remedies can interfere with it. In particular, do not take indigestion remedies, or supplements containing iron, magnesium, or zinc at the same time as you take demeclocycline. This is because demeclocycline combines with these things, which makes it less effective. If you need to take an antacid or any of the supplements mentioned, make sure you leave at least two hours before or after taking demeclocycline before you have them.

  • Some people develop thrush (redness and itchiness in the mouth or vagina) after taking a course of an antibiotic. If this happens to you, speak with your doctor or pharmacist for advice.

  • Demeclocycline can cause your skin to become more sensitive to sunlight than usual. Avoid strong sunlight and sunbeds, and use a sun cream with a high sun protection factor on bright days, even when it is cloudy.

  • This antibiotic can stop the oral typhoid vaccine from working. If you are due to have any vaccinations, make sure the person treating you knows that you are taking this medicine.

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Can demeclocycline cause problems?

Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the ones associated with demeclocycline. The best place to find a full list of the side-effects which can be associated with your medicine, is from the manufacturer's printed information leaflet supplied with the medicine. Alternatively, you can find an example of a manufacturer's information leaflet in the reference section below. Speak with your doctor or pharmacist if any of the following continue or become troublesome.

Demeclocycline side-effects

What can I do if I experience this?

Stomach upset, tummy (abdominal) pain

Stick to simple foods - avoid fatty or spicy meals


Drink plenty of water to replace lost fluids. If this continues or is severe, speak with a doctor


Drink plenty of water and ask a pharmacist to recommend a suitable painkiller. If the headaches continue, let your doctor know

Feeling dizzy, blurred vision

Do not drive and do not use tools or machines while affected. If it continues, speak with your doctor

Important: demeclocycline can occasionally cause allergic reactions, such as a skin rash. Speak with a doctor as soon as possible if this happens to you.

If you experience any other symptoms which you think may be due to the medicine, speak with your doctor or pharmacist for further advice.

How to store demeclocycline

  • Keep all medicines out of the reach and sight of children.

  • Store in a cool, dry place, away from direct heat and light.

Important information about all medicines

Important information about all medicines

Never take more than the prescribed dose. If you suspect that you or someone else might have taken an overdose of this medicine go to the accident and emergency department of your local hospital. Take the container with you, even if it is empty.

If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are taking.

This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.

Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.

If you have any questions about this medicine ask your pharmacist.

Report side effects to a medicine or vaccine

If you experience side effects, you can report them online through the Yellow Card website.

Further reading and references

Article history

The information on this page is written and peer reviewed by qualified clinicians.

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