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Patient Guide



About your medicine

Your doctor has prescribed one of the following medicines for you:

  • Doxycycline
  • Minocycline
  • Tetracycline

What are these medicines used for?

These medicines are used to treat infections.

They are also used for the treatment of acne by suppressing the growth of the acne bacteria and decreasing the inflammation caused by the bacteria.

How should you take these medicines?

If you are taking doxycycline or minocycline :
  • These medicines should be taken together with some food especially if nausea or stomach discomfort occurs.
  • Avoid taking antacids or products containing calcium or iron together with this medicine. These may reduce the effectiveness of doxycycline or minocycline. You can take these 2 hours before or after your medicine.

For patients taking tetracycline:
  • Take tetracycline on an empty stomach, either 1 hour before or 2 hours after meals, for better absorption. However, if it upsets your stomach, you should take it with some food.
  • Avoid taking milk or dairy products, antacids or products containing calcium or iron together with tetracycline. These may reduce the effectiveness of tetracycline. You can take these 2 hours before or after tetracycline.

These medicines should be taken with a glass of water to prevent irritation of the oesophagus (gullet). Avoid lying down for at least 30 mins after ingestion.

For effective treatment, you should complete the full course of medication prescribed even though there are signs of improvement.

What should you do if you forget a dose?

Take the missed dose as soon as you remember. If it is almost time for the next dose, skip the missed dose.

Do not double the next dose to make up for the missed dose.

What are the possible side effects of these medicines?

In the treatment of acne, these medicines are usually given for about 4 to 6 months. If the acne is not controlled, these medicines can be taken for longer periods without any serious side effects.

Certain side effects of these medicines are not unusual and may even disappear during treatment. If any of the following effects persist or are severe, consult your doctor:

  • Nausea, vomiting, stomachache or “wind” in the stomach (if it occurs with doxycycline, taking it halfway during a meal may help)
  • Diarrhoea
  • Itching of the genital areas; sore mouth or tongue. This may indicate a yeast infection, which may need treatment if severe
  • Increased sensitivity of skin to sunlight resulting in a skin rash, itching, redness, discoloration or severe sunburn. You will need to avoid prolonged exposure to strong sunlight if this occur.

Stop the medication and consult your doctor if you develop any new rash soon after starting the medication.

For patients taking minocycline:
  • Minocycline may also cause dizziness or lightheadedness. If affected, do not drive or operate machinery
  • This medicine may rarely cause blue-black pigmentation in the skin at the site of acne scars or elsewhere on the body. Inform your doctor if you notice any unusual pigmentation.
  • Minocycline may rarely cause liver inflammation. It may also very rarely result in a disease called lupus erythematosus but this is extremely rare.

What precautions should you take?

  • For women: Tell your doctor if you are pregnant, planning to become pregnant, or are breast-feeding as these medicines may affect the bones and teeth of the baby (*see below).
  • These medicines may reduce the effectiveness of your oral contraceptives and increase the chance of unwanted pregnancy.
  • Young children under 12 years of age should not take these medicines as the medicines can cause discoloration of teeth and also slow down the growth of bones*.
  • • Tetracyclines may have drug interactions with some other medications. If taken concurrently, these medicines may increase the blood level of the other medications such as methotrexate and warfarin. Tetracyclines should NOT be taken concurrently with acitretin or isotretinoin, due to an increased risk of high pressure in the head leading to headaches, nausea and vomiting.
  • Inform your doctor if you are taking over-the-counter medicines, including vitamins, minerals, and herbal products.
  • Do not allow anyone else to take this medication.

How do you store this medicine?

  • Keep these medicines away from heat and direct sunlight in a cool, dry place, out of reach of children.
  • Do not keep these medicines with other medications in the same container. Keep each medicine separately in labeled containers.
  • Discard all expired medicines as expired products may be harmful.

When in doubt, consult your doctor or pharmacist.
National Skin Centre (Singapore)
1 Mandalay Road, Singapore 308205
Tel: 63508454


Last updated on 05 May 2020

Last updated on 05 May 2020