Multiple sclerosis (MS) is an autoimmune disorder in which your immune system attacks the protective coating around nerves in your central nervous system (CNS). The CNS includes your brain and spinal cord.

Disease-modifying therapies (DMTs) are the recommended treatment to help slow the development of MS. DMTs may help delay disability and reduce the frequency of flares in people with the condition.

The Food and Drug Administration (FDA) has approved multiple DMTs to treat relapsing forms of MS, including six DMTs that are taken orally as capsules or tablets.

Read on to learn more about oral DMTs and how they work.

To understand how oral DMTS help treat MS, you need to know about the role of certain immune cells in MS.

Many types of immune cells and molecules are involved in the abnormal immune response that causes the inflammation and damage in MS.

These include T cells and B cells, two types of white blood cell known as lymphocytes. They’re produced in your body’s lymphatic system.

When T cells move from your lymphatic system into your bloodstream, they can travel to your CNS.

Certain types of T cells produce proteins known as cytokines, which trigger inflammation. In people with MS, pro-inflammatory cytokines cause damage to myelin and nerve cells.

B cells also produce pro-inflammatory cytokines, which may help drive the activities of disease-causing T cells in MS. B cells also produce antibodies, which may play a role in MS.

Many DMTs work by limiting the activation, survival, or movement of T cells, B cells, or both. This helps reduce inflammation and damage in the CNS. Some DMTs protect nerve cells from damage in other ways.

The FDA has approved the use of cladribine (Mavenclad) to treat relapsing forms of MS in adults. To date, no studies have been completed on the use of Mavenclad in children.

When someone takes this medication, it enters into T cells and B cells in their body and interferes with the cells’ ability to synthesize and repair DNA. This causes the cells to die, reducing the number T cells and B cells in their immune system.

If you receive treatment with Mavenclad, you’ll take two courses of the drug over 2 years. Each course will involve 2 treatment weeks, separated by 1 month.

During each treatment week, your doctor will advise you to take one or two daily doses of the drug for 4 or 5 days.

The FDA has approved dimethyl fumarate (Tecfidera) for treating relapsing forms of MS in adults.

The FDA hasn’t yet approved Tecfidera for treating MS in children. However, doctors may prescribe this medication to children in a practice known as “off-label” use.

Although more research is needed, studies to date suggest this drug is safe and effective for treating MS in children.

Experts don’t know exactly how Tecfidera works. However, researchers have found this medication may reduce the abundance of certain kinds of T cells and B cells, as well as pro-inflammatory cytokines.

Tecfidera also appears to activate a protein known as nuclear factor erythroid 2-related factor (NRF2). This triggers cellular responses that help protect nerve cells from oxidative stress.

If you’re prescribed Tecfidera, your doctor will advise you to take two 120-milligram (mg) doses per day for the first 7 days of treatment. After the first week, they’ll tell you to take two 240-mg doses per day on an ongoing basis.

The FDA has approved diroximel fumarate (Vumerity) to treat relapsing forms of MS in adults. Experts don’t yet know whether this medication is safe or effective in children.

Vumerity is part of the same class of medications as Tecfidera. Like Tecfidera, it’s believed to activate the protein NRF2. This sets off cellular responses that help prevent damage to nerve cells.

If your treatment plan includes Vumerity, your doctor will advise you to take 231 mg of the medication twice per day for the first 7 days. From that point on, you should then take 462 mg of the medication twice per day.

The FDA has approved fingolimod (Gilenya) for treating relapsing forms of MS in adults as well as children ages 10 years or older.

The FDA hasn’t yet approved this medication for treating younger children, but doctors may prescribe it off-label to kids under the age of 10.

This medication blocks a type of signaling molecule known as sphingosine 1-phosphate (S1P) from binding to T cells and B cells. In turn, this prevents those cells from entering the bloodstream and traveling to the CNS.

When those cells are stopped from traveling to the CNS, they can’t cause inflammation and damage there.

Gilenya is taken once a day. In people who weigh more than 88 pounds (40 kilograms), the recommended daily dose is 0.5 mg. In those who weigh less than that, the recommended daily dose is 0.25 mg.

If you start treatment with this medication and then stop using it, you may experience a severe flare.

Some people with MS have developed a severe increase in disability and new brain lesions after they stop taking this medication.

The FDA has approved siponimod (Mayzent) for treating relapsing forms of MS in adults. So far, researchers haven’t completed any studies on the use of this medication in children.

Mayzent is in the same class of drugs as Gilenya. Like Gilenya, it blocks S1P from binding to T cells and B cells. This stops those immune cells from traveling to the brain and spinal cord, where they can cause damage.

Mayzent is taken once per day. To determine your optimum daily dosage, your doctor will start by screening you for a genetic marker that can help predict your response to this medication.

It your genetic test results suggest this medication might work well for you, your doctor will prescribe a small dose to start. They’ll gradually increase your prescribed dose in a process of known as titration. The goal is to optimize potential benefits while limiting side effects.

If you take this medication and then stop using it, your condition might get worse.

The FDA has approved the use of teriflunomide (Aubagio) for treating relapsing forms of MS in adults. No studies have been published so far on the use of this drug in children.

Aubagio blocks an enzyme known as dihydroorotate dehydrogenase (DHODH). This enzyme is involved in the production of pyrimidine, a DNA building block that’s required for DNA synthesis in T cells and B cells.

When this enzyme can’t access enough pyrimidine to synthesize DNA, it limits the formation of new T cells and B cells.

If you receive treatment with Aubagio, your doctor may prescribe a 7- or 14-mg daily dose.

In addition to these oral medications, the FDA has approved a number of DMTs that are injected under the skin or given via intravenous infusion.

They include:

  • alemtuzumab (Lemtrada)
  • glatiramer acetate (Copaxone, Glatect)
  • interferon beta-1 (Avonex)
  • interferon beta-1a (Rebif)
  • interferon beta-1b (Betaseron, Extavia)
  • mitoxantrone (Novantrone)
  • natalizumab (Tysabri)
  • ocrelizumab (Ocrevus)
  • peginterferon beta-1a (Plegridy)

Talk to your doctor to learn more about these medications.

Treatment with DMTs can cause side effects, which in some cases are serious.

The potential side effects of treatment vary depending on the specific type of DMT you take.

Some common side effects include:

  • headache
  • nausea
  • vomiting
  • diarrhea
  • skin rash
  • hair loss
  • slow heart rate
  • facial flushing
  • abdominal discomfort

DMTs are also linked to increased risk of infection, such as:

  • influenza
  • bronchitis
  • tuberculosis
  • shingles
  • certain fungal infections
  • progressive multifocal leukoencephalopathy, a rare type of brain infection

The increased risk of infection is because these medications alter your immune system and may lower the number of disease-fighting white blood cells in your body.

DMTs may cause other serious side effects, such as liver damage and serious allergic reactions. Some DMTs may cause your blood pressure to rise. Some may cause your heart rate to slow.

Keep in mind that your doctor will recommend a DMT if they believe the potential benefits outweigh the risks.

Living with MS that isn’t effectively managed also carries significant risks. Talk to your doctor to learn more about the potential side effects and benefits of different DMTs.

DMTs aren’t generally considered safe for people who are pregnant or breastfeeding.

Before you start treatment with a DMT, your doctor should screen you for active infections, liver damage, and other health problems that might raise the risks of taking the medication.

Your doctor may also encourage you to receive certain vaccinations before you begin treatment with a DMT. You may need to wait several weeks after receiving vaccinations before you start taking the drug.

While you’re receiving treatment with a DMT, your doctor might advise you to avoid certain medications, nutritional supplements, or other products. Ask them if there are any medications or other products that could interact or interfere with the DMT.

Your doctor should also monitor you for signs of side effects during and after treatment with a DMT. For example, they’ll likely order regular blood tests to check your blood cell count and liver enzymes.

If you think you might be experiencing side effects, let your doctor know right away.

Multiple DMTs have been approved to treat MS, including six types of oral therapy.

Some of these medications may be safer or better suited to certain people than others.

Before you start taking a DMT, ask your doctor about the potential benefits and risks of using it. They can help you understand how different treatments might affect your body and long-term outlook with MS.