Minocycline is an antibiotic that reduces inflammation. Doctors usually use minocycline for the treatment of bacterial infections such as pneumonia, but one off-label use is to help treat rheumatoid arthritis (RA). That said, newer treatments for RA are now more common than minocycline.

Minocycline is an antibiotic in the tetracycline class. The usual dosage for minocycline is 100 milligrams twice daily (or every 12 hours) by mouth. Although its intended purpose is to help treat bacterial infections, doctors have also used it as a disease modifying antirheumatic drug (DMARD). DMARDs can improve the symptoms of RA and prevent long-term disabilities. This article looks at minocycline as a treatment for RA, its effectiveness and side effects, and other more common treatments.

Can minocycline help treat RA?

Some research suggests that minocycline can relieve the symptoms of RA. It seems to be more effective in the early stages of the condition. Evidence from research published the 1990s suggests that minocycline can improve:

• Joint swelling and tenderness
• Markers of inflammation

Although minocycline can reduce inflammation, swelling, and tenderness, it does not completely stop disease progression. Doctors now use minocycline sparingly in the treatment of RA because new agents and other DMARDs are more effective in reducing the symptoms and slowing its progression. Researchers have also studied it less than other treatment options.

The American College of Rheumatology's most recent recommendations for the treatment of RA do not suggest minocycline. This is because doctors rarely use minocycline as a treatment for RA, and because there is a lack of new data on its use since 2012.

How does it work?

RA is an autoimmune condition that causes inflammation and damages the joints and nearby tissue. Inflammation and inflammation signals in joints are the main features of RA. Minocycline can help treat RA by slowing down the immune system and reducing inflammation. This stops joint damage.

Many cell types and cell signals fuel the process of inflammation, but the specifics of these processes can vary between inflammatory conditions. The amount of inflammation will determine the type of therapy needed to control the symptoms. The same level of inflammation, however, can respond differently to different treatments.

Doctors typically use minocycline as an antibiotic to treat a wide variety of bacterial infections. Although it is an antibiotic, minocycline can ease RA symptoms in ways not directly related to its antibiotic properties. Some studies suggest that minocycline may work for RA by blocking inflammatory signals and dampening the immune system.

Side effects

Minocycline has fewer adverse effects than other drugs that treat RA. However, some adverse effects of minocycline include:

• Nausea
• Vomiting
• Diarrhea
• Sun sensitivity
• Headache
• Lightheadedness
• Fingernail and skin discoloration, or hyperpigmentation
• Appetite changes

People may notice blue or black skin discoloration on the arms and legs. This usually happens in areas of previous injuries. Minocycline can also discolor a person's teeth.

Although minocycline is effective for treating a range of autoimmune conditions, in very rare cases, it can cause symptoms similar to those of an autoimmune condition called lupus erythematosus. This condition can involve joint pain, joint inflammation, fever, and muscle pain. Other, rare adverse reactions can include inflammation in the liver, lungs, or kidneys.

Alternative medications for RA

The following four options are the main treatment options for RA:

• DMARDs
• Biological agents
• Tofacitinib
• Glucocorticoids

A doctor will determine the drug to prescribe based on how long the person has had RA and the severity of their symptoms. They may add or switch drugs if a person's symptoms worsen.

DMARDs

DMARDs, a collection of unrelated drugs, form the foundation of RA treatment. The most common DMARDS are:

• Hydroxychloroquine
• Leflunomide
• Methotrexate
• Sulfasalazine

The American College of Rheumatology recommendations suggest using methotrexate alone as the first treatment in people who have had RA for under 6 months. Doctors may suggest using DMARDs alone or in combination therapy (methotrexate plus sulfasalazine or methotrexate plus sulfasalazine plus hydroxychloroquine). The guidelines generally recommend that doctors use a single drug as an initial treatment because it costs less and causes fewer adverse effects. A single agent is also easier for a person to take. DMARDs can reduce long-term disability, but they also can cause significant adverse effects. When compared with glucocorticoids, DMARDs take longer to work.

Biologics

Biological agents fall into two classes: tumor necrosis factor (TNF) inhibitors and non-TNF.

The following drugs are in the TNF class:

• Adalimumab (Humira)
• Etanercept (Enbrel)
• Infliximab (Remicade)
• Certolizumab pegol (Cimzia)
• Golimumab (Simponi)

These drugs work by disrupting and disarming a critical inflammatory signal in the joints. People who take these agents are at increased risk of infections. Doctors should screen people for hepatitis B and hepatitis C before starting treatment with a TNF drug.

The guidelines recommend these drugs for people with moderate or severe cases of RA. Often, doctors recommend these drugs for people with RA that has progressed beyond DMARD treatment. When possible, doctors should combine TNF inhibitors with methotrexate because this improves their benefits.

The following drugs are in the non-TNF class:

• Abatacept (Orencia)
• Rituximab (Rituxan)
• Tocilizumab (Actemra)

Orencia and Actemra work by hindering immune system activity, which thereby reduces inflammation. Rituxan cancels out specific immune cells involved in inflammation.

Tofacitinib

Tofacitinib (Xeljanz) is in a category by itself. This drug stops the signals within inflammatory cells. Stopping these signals halts inflammatory cell activity.

Glucocorticoids

Glucocorticoids are a type of steroid hormone. They work by suppressing the immune cells responsible for inflammation. This reduces inflammation in the body. Doctors can use a variety of glucocorticoids to treat RA. The dosages and length of treatment may vary depending on the severity of the condition. People tend to get the best results from using glucocorticoids for short periods of time to treat flare-ups. People with RA do not usually use glucocorticoids for longer than 3 months due to the adverse effects they cause, such as infections and osteoporosis. Learn more about steroids for RA here.

Summary

Over the past 20 years, gaining official approval of biological agents and developing a better understanding of DMARDs has changed the face of RA treatment. These changes have placed minocycline outside the circle of standard treatment options for RA.

Researchers have stopped investigating minocycline for the treatment of RA. The most recent guidelines do not recommend minocycline because other options are more beneficial. Minocycline now plays a small and retreating role in the treatment of RA.