How does this medication work? What will it do for me?

Tetracycline belongs to the class of medications called antibiotics. It is used to treat certain types of infections that are caused by bacteria (antibiotics are not useful for viruses like the ones that cause the common cold).

Tetracycline is most commonly used to treat infections of the skin (including acne), Lyme disease, and certain sexually transmitted infections. Tetracycline is also used in combination with bismuth subsalicylate, another antibiotic called metronidazole, and a proton pump inhibitor such as omeprazole for treatment of the bacteria (H. pylori) that cause a majority of stomach ulcers.

Your doctor may have suggested this medication for conditions other than those listed in these drug information articles. As well, some forms of this medication may not be used for all of the conditions discussed here. If you have not discussed this with your doctor or are not sure why you are taking this medication, speak to your doctor. Do not stop taking this medication without consulting your doctor.

Do not give this medication to anyone else, even if they have the same symptoms as you do. It can be harmful for people to take this medication if their doctor has not prescribed it.

What form(s) does this medication come in?

This medication is available as a 250 mg tablet.

How should I use this medication?

The recommended adult dose of tetracycline is 250 mg to 500 mg 4 times daily on an empty stomach. For 2 hours before and after taking the medication, avoid dairy products as well as antacids that contain aluminum, calcium, or magnesium. Tetracycline should be taken with a full glass of water while standing or sitting upright and should not be taken at bedtime (to avoid irritation of the lining of the throat and the tube leading to the stomach, known as the esophagus).

Many things can affect the dose of medication that a person needs, such as body weight, other medical conditions, and other medications. If your doctor has recommended a dose different from the ones listed here, do not change the way that you are taking the medication without consulting your doctor.

It is important to take this medication exactly as prescribed by the doctor. Finish all this medication, even if you have started to feel better. If you miss a dose, take it as soon as possible and continue with your regular schedule. If it is almost time for your next dose, skip the missed dose and continue with your regular dosing schedule. Do not take a double dose to make up for a missed one. If you are not sure what to do after missing a dose, contact your doctor or pharmacist for advice.

Do not dispose of medications in wastewater (e.g. down the sink or in the toilet) or in household garbage. Ask your pharmacist how to dispose of medications that are no longer needed or have expired.

Who should NOT take this medication?

Do not take this medication if you:

  • are allergic to tetracycline or any ingredients of this medication
  • are allergic to related medications such as doxycycline or minocycline
  • are pregnant or breast-feeding (unless the benefits outweigh the risks)
  • have severe reduction in kidney function

Do not give this medication to children under 8 years of age who have a common infection that may be treated with a different antibiotic.

What side effects are possible with this medication?

Many medications can cause side effects. A side effect is an unwanted response to a medication when it is taken in normal doses. Side effects can be mild or severe, temporary or permanent.

The side effects listed below are not experienced by everyone who takes this medication. If you are concerned about side effects, discuss the risks and benefits of this medication with your doctor.

The following side effects have been reported by at least 1% of people taking this medication. Many of these side effects can be managed, and some may go away on their own over time.

Contact your doctor if you experience these side effects and they are severe or bothersome. Your pharmacist may be able to advise you on managing side effects.

  • abdominal pain
  • diarrhea
  • increased skin sensitivity to sunlight
  • nausea and vomiting
  • vaginal yeast infections

Although most of the side effects listed below don't happen very often, they could lead to serious problems if you do not seek medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

  • hepatic cholestasis, or blockage of bile flow (a digestive fluid) from the liver; symptoms may include yellowing of the skin or eyes, intense itching and/or dark coloured urine

Stop taking the medication and seek immediate medical attention if any of the following occur:

  • bulging soft spot on the heads of infants (which may also be a result of increased pressure in the skull)
  • increased pressure in the skull (also known as intracranial pressure). Patients may experience headache and/or visual disturbances as a result
  • serious allergic reaction (e.g. difficulty breathing)

Some people may experience side effects other than those listed. Check with your doctor if you notice any symptom that worries you while you are taking this medication.

Are there any other precautions or warnings for this medication?

Before you begin using a medication, be sure to inform your doctor of any medical conditions or allergies you may have, any medications you are taking, whether you are pregnant or breast-feeding, and any other significant facts about your health. These factors may affect how you should use this medication.

Diarrhea: If you develop diarrhea while taking tetracycline, call your doctor.

Kidney function: People with reduced kidney function should take tetracycline with caution and use an adjusted dose, as prescribed by their doctor. People with severely reduced kidney function are at risk of significant side effects with the use of this medication.

Overgrowth of organisms: The use of antibiotics may allow organisms not killed by the antibiotic to overgrow. This may cause unwanted conditions such as yeast infections.

Sensitivity to sunlight: An exaggerated sunburn reaction may occur for some people who take this medication. Watch for this if you spend time in direct sunlight or ultraviolet light and ensure that sun protection measures are taken (e.g., wear sunscreen, a hat, and long sleeve shirts). At the first sign of skin redness, stop taking the medication and see your doctor about changing your prescription.

Tooth discolouration: The use of tetracycline during tooth development (from the second trimester of pregnancy to the age of 8 years) may cause permanent discoloration of the teeth (yellow-grey-brown). Though more commonly associated with long-term use of tetracyclines, this effect has also been known to occur after taking the medication for a short time. Tetracycline should therefore not be used by children 8 years old or younger unless other medications are unlikely to be effective or can't be used.

Pregnancy: This medication should not be used during pregnancy unless the benefits outweigh the risks. If you become pregnant while taking this medication, contact your doctor immediately.

Breast-feeding: This medication passes in small amounts into breast milk. Tetracycline is not recommended for nursing women unless potential benefits outweigh the risks.

What other drugs could interact with this medication?

There may be an interaction between tetracycline and any of the following:

  • antacids that contain aluminum, calcium, or magnesium
  • birth control medications
  • bismuth subsalicylate
  • calcium supplements
  • cholestyramine
  • colestipol
  • digoxin
  • insulin
  • iron supplements
  • lithium
  • kaolin and pectin
  • penicillin
  • vitamin A derivatives (e.g. isotretinoin)
  • warfarin
  • zinc sulfate or gluconate

If you are taking any of these medications, speak with your doctor or pharmacist. Depending on your specific circumstances, your doctor may want you to:

  • stop taking one of the medications,
  • change one of the medications to another,
  • change how you are taking one or both of the medications, or
  • leave everything as is.

An interaction between two medications does not always mean that you must stop taking one of them. Speak to your doctor about how any drug interactions are being managed or should be managed.

Medications other than those listed above may interact with this medication. Tell your doctor or prescriber about all prescription, over-the-counter (non-prescription), and herbal medications you are taking. Also tell them about any supplements you take. Since caffeine, alcohol, the nicotine from cigarettes, or street drugs can affect the action of many medications, you should let your prescriber know if you use them.