Antibiotics may be used as a treatment for rheumatoid arthritis (RA), particularly in people who are in the earliest stages of the disease. In the past, antibiotics were used as a treatment for RA because doctors believed all disease was caused by germs.
While we now know that there are multiple factors that likely play a role in the cause of RA, including a genetic susceptibility and exposures to environmental factors, researchers have identified some bacteria that may be part of the environmental contributors to RA.1,2
The antibiotics most often used in treating RA belong to a class called tetracyclines, and the tetracycline that is most frequently used is minocycline (Minocin).2
Minocycline (Minocin) is an oral antibiotic. Although it is not approved by the U.S. Food and Drug Administration for RA, it has been studied as a treatment in people with RA.2
It is not known exactly how tetracyclines work to improve symptoms in RA, but potential mechanisms include their action in decreasing the production of chemicals that regulate the immune response and chemicals that play a role in joint destruction. Evidence of the effectiveness of minocycline comes from several randomized, controlled trials. The greatest benefit appears to be when it is used early in the course of RA.
A review of several studies of minocycline in RA conducted in over 500 patients found that minocycline or another tetracycline resulted in significant improvements in joint pain, tenderness and swelling, physical functioning, and inflammatory markers compared with placebo. In a study comparing minocycline to hydroxychloroquine, at 2 years minocycline resulted in a significantly higher rate of ACR50 response (60% versus 33%; P=0.04).3
Common side effects of minocycline
The most common side effects associated with minocycline include rash, headaches, dizziness, gastrointestinal (GI) side effects (nausea, vomiting, and diarrhea). These are not all the possible side effects of minocycline. Patients should talk to their doctor about what to expect with treatment with minocycline.3,4
Limitations of antibiotic therapy for RA
Minocycline is not widely used to treat RA because of several factors. It has demonstrated some effectiveness in certain people when they are treated early in the course of their disease. However, the use of antibiotics doesn’t stop the disease from progressing in all people with RA, and when RA progresses, it can cause irreversible damage to the joints.
Compared to other treatments, like disease-modifying anti-rheumatic drugs (DMARDs), minocycline is a relatively weak therapy.1