Minocycline (Minocin)

medication bottles

Fast Facts

  • Minocycline is sometimes used to treat mild rheumatoid arthritis.
  • It belongs to the group of tetracycline antibiotics which often are used to treat infections.
  • Minocycline has a slow onset and may take several months to work.
  • Minocycline should not be given during pregnancy or used when breastfeeding.
  • Before taking minocycline, tell your doctor if you have ever had any unusual or allergic reaction to any other tetracycline antibiotic.
  • Minocycline is passed into breast milk, so mothers should avoid breast-feeding in order to prevent delayed development of teeth and bones in their infants. Minocycline can increase a nursing infant’s risk of fungal infections or dizziness.
  • Because minocycline may cause discoloration of teeth and problems with bone growth in young children, it is recommended that those younger than 8 years old do not take this medication. This is not a problem in older children and adults.

Minocycline (Minocin) is an antibiotic sometimes used to treat rheumatoid arthritis (RA). It is part of the group of antibiotics known as tetracyclines. Although RA is not thought to be caused by an infection, minocycline may improve the signs and symptoms of this disease. Minocycline also belongs to the class of drugs known as DMARDs (disease-modifying anti-rheumatic drugs).


Minocycline is prescribed for patients with symptoms of mild rheumatoid arthritis. It is sometimes used in combination with other medications. Because it has been studied less and may be less effective than other options, it is not commonly prescribed in RA.

How it works

Minocycline is an antibiotic, which means it helps stop or kill bacteria that cause infections. However, when used to treat RA, minocycline works differently to control inflammation. Minocycline decreases the production of substances causing inflammation, such as prostaglandins, metalloproteinases and leukotrienes. It also increases production of interleukin-10, a substance that reduces inflammation.


Minocycline usually is given as a 100 milligram (mg) capsule twice a day. It may be taken with food but should not be taken with other medications such as antacids or iron tablets.

Time to effect

It may take two to three months to notice improvement of your arthritis symptoms, and it could take up to a year before you receive its maximum benefits

Side effects

The most common side effects from this medicine are gastrointestinal (stomach or intestines) symptoms, dizziness and skin rash. Patients who take this medication for a long time may notice changes in their skin color, but this usually resolves after stopping the medication.

Some women who take minocycline develop vaginal yeast infections. While this can occur with other antibiotics, it seems more common with minocycline and other tetracyclines. It is believed that minocycline kills bacteria that are normally present in the body that protect against yeast infections.

Minocycline may increase sensitivity to sunlight, resulting in more frequent sunburns or the development of rashes following sun exposure. It is recommended that patients apply sunscreen (SPF 15 or greater) before outdoor activities or avoid prolonged exposure to the sun while taking minocycline.

More rarely, minocycline can affect the kidneys or liver. Doctors may recommend periodic blood tests for long-term users to check liver and kidney function. In equally rare cases, minocycline can induce lupus, but this condition usually improves after stopping the medication.

Drug interactions

Be sure to tell your doctor about all of the medications you are taking, including over-the-counter drugs and natural remedies. Possible interactions with minocycline may occur when taking warfarin (Coumadin), antacids containing calcium, aluminum or magnesium (such as Tums, Rolaids, Maalox, or Mylanta), iron tablets, oral contraceptives (birth control pills), tretinion (“retinoids”), Accutane, Soriatane and methotrexate.

Information to discuss with health care providers

Be sure to notify your other physicians that you are taking this drug. Women taking this medication should discuss appropriate forms of birth control with their primary care physician or gynecologist. Minocyline is not recommended for use during pregnancy. It can slow the growth of teeth or bones in infants after birth and also can cause discoloration of the newborn’s teeth when taken during the last half of pregnancy. It is also important to remember minocycline may reduce the effectiveness of some birth control pills.

Updated March 2015 by Michael Cannon, MD, and reviewed by the American College of Rheumatology Committee on Communications and Marketing.

This patient fact sheet is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.

© 2015 American College of Rheumatology