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 Tetracycline. If you are concerned about side effects, discuss the risks and benefits of Tetracycline with your doctor.

The following side effects have been reported by at least 1% of people taking Tetracycline. 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 Tetracycline.

Do not take Tetracycline if you:

• are allergic to tetracycline or any ingredients of Tetracycline
• 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 Tetracycline to children under 8 years of age who have a common infection that may be treated with a different antibiotic.

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 Tetracycline. 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.

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 Tetracycline.

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 Tetracycline.

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

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