Along with its needed effects, minocycline may cause some unwanted or undesirable effects. Generally, minocycline is well tolerated and many people will not experience unwanted effects. The frequency and severity of these effects is dependent on many factors including dose, duration of therapy and individual susceptibility. Possible unwanted effects include:

• diarrhea
• dizziness
• lightheadedness
• vertigo (feeling of whirling sensation)
• headache
• vomiting
• nausea
• gas
• stomach upset
• appetite loss
• discoloration of bones and teeth in children under the age of 13 and in children of mothers given minocycline during the last half of her pregnancy

Uncommon:

• rash
• hives
• sensitivity to sunlight
• allergic reaction (e.g. rash, itching, difficulty breathing)
• inflammation of the lining of the mouth
• inflammation of the tongue

Rare:

• sore mouth and tongue

Unwanted effects associated with the stomach should be reported to your pharmacist if they persist or become bothersome. Any uncommon or rare, unwanted effects should be reported to your pharmacist immediately.

Minocycline is an antibiotic medication that kills various bacteria. It works by inhibiting the bacteria's production of protein. This slows and prevents it's growth and reproduction. The effectiveness of minocycline depends on factors such as dose, concentration in the blood as well as other body fluids and tissue, and susceptibility of the organism. Minocycline affects only certain types of bacteria sensitive to its antibiotic action. Infections caused by bacteria that are not sensitive to minocycline will not show improvement after taking this medication.

Allergic reactions can occur with minocycline use. People with a history of allergy, asthma, hay fever or hives seem to be more susceptible to these reactions. The reaction can be immediate and severe. Allergic symptoms include wheezing, hives, itching, swelling, spasms in the throat and breathing tubes, joint and muscle pain, difficulty breathing, fever and skin rashes. Nausea and vomiting are not symptoms of an allergic reaction.

Use of minocycline in children umder 13 years of age is not recommended. Use of minocycline in this age group, during tooth development has been known to cause permanent tooth discoloration. It has also been known to decrease bone growth when given to premature infants.
Avoid prolonged exposure to direct sunlight or tanning beds. Some people may develop a sensitivity to sunlight while taking minocycline that usually presents itself in the form of a rash and/or a painful burn. Sun screen and protective clothing should be worn as a precautionary measure when exposed to direct sunlight. Some people being treated with minocycline experience dizziness, light-headedness, vertigo (feeling of whirling sensation) and headache. These symptoms may disappear during therapy and usually disappear rapidly when therapy is finished. Minocycline belongs to the tetracycline group of antibiotics. If you are allergic to a tetracycline (e.g. doxycycline, tetracycline), you may also be allergic to minocycline.
Antacids containing aluminum, magnesium or calcium and oral iron preparations interfere with the absorption of minocycline and should be avoided.

Taking the antibiotic repeatedly or for prolonged periods may result in bacterial or fungal overgrowth which can lead to a second infection. When this occurs, the minocycline may need to be stopped and another antibiotic prescribed to treat the new infection.
Diarrhea can develop while taking minocycline. This is sometimes caused by an overgrowth of bacteria in the gut that are not killed by the antibiotic. In severe cases, this may be life threatening and would require treatment with other antibiotics. In mild cases, symptoms disappear shortly after the drug is discontinued.
Drug Interactions: It is important to tell your doctor and pharmacist of any prescription or over-the-counter medications you are taking. In some cases, the dose of one or both drugs may need to be altered or another drug may be prescribed. The following drugs or drug classes have been known to interact with minocycline:

• oral contraceptives (e.g. Triphasil®)
• antacids containing aluminum, magnesium or calcium
• bismuth salts (e.g. Pepto-Bismol®)
• warfarin (e.g. Coumadin®)
• penicillins
• digoxin (e.g. Lanoxin®)
• oral iron preparations (e.g. Palafer®)

Use is not recommended in the following situations:

• allergy to any tetracycline (e.g. tetracycline, doxycycline)

Caution is recommended in the following situations:

• children under 13 years of age
• allergies
• kidney disease
• liver disease

Use in pregnancy: Minocycline is not recommended during pregnancy because of possible adverse effects on developing bones and teeth of the unborn baby. Consult your doctor or pharmacist if you suspect you are pregnant.
Use while breastfeeding: Minocycline does appear in breast-milk. Medications in this family are generally considered appropriate for use in breastfeeding, however, consult your doctor or pharmacist before using.