Oral therapies

These oral DMTs are approved for treating relapsing MS.

Fingolimod (Gilenya). This once-daily oral medication reduces the relapse rate of MS. Fingolimod is a unique medication that binds to many different types of body cells. It traps white blood cells in lymph nodes so that they can't enter the brain and cause new MS lesions.

People with heart disorders or related conditions can't use fingolimod. It can temporarily slow the heart rate, so the first dose must be taken under medical supervision. It also requires monitoring of vision because of a risk of buildup of fluid in the macula, an area in the center of the retina. For that reason, people with diabetes generally shouldn't use fingolimod.

Teriflunomide (Aubagio). Teriflunomide has been approved in two doses, 7 milligrams (mg) and 14 mg, taken once daily. It's generally well tolerated at both doses. Possible side effects include headache, diarrhea, nausea, elevation in liver enzymes and hair thinning.

Pregnant women and people with liver conditions shouldn't use teriflunomide.

Dimethyl fumarate (Tecfidera). Also known as BG-12, dimethyl fumarate is taken twice daily. Common side effects include flushing and gastrointestinal problems, such as diarrhea and nausea. Its coating is designed to reduce gastrointestinal problems, and taking it with food also can help relieve them.

Diroximel fumarate (Vumerity). This twice-daily capsule is similar to dimethyl fumarate but typically causes fewer side effects. It's approved for the treatment of relapsing forms of MS.

Cladribine (Mavenclad). This drug has been shown to be effective in reducing MS relapses and new brain lesions. It was also approved for secondary-progressive MS. Possible side effects include increased risk of developing infections.

Siponimod (Mayzent). This once-daily oral medication can reduce relapse rate and help slow the progression of MS. It's also approved for secondary-progressive MS.

Possible side effects include viral infections, liver problems and low white blood cell count. Other possible side effects include changes in heart rate, headaches and vision problems.