Methotrexate for Myositis

How does methotrexate work?

Our immune system acts like the body's defence army. In myositis, parts of this immune army become overactive and begin attacking healthy muscle tissue by mistake. Methotrexate works by calming down this overactive immune response.

In simple terms, methotrexate:

• Reduces the activity of immune cells that drive inflammation
• Lowers the production of inflammatory chemicals that damage muscles
• Increases the level of natural anti-inflammatory signals in the body
• Helps reduce the cycle of ongoing muscle inflammation and injury

The goal

The goal is not to switch off immunity completely, but to bring it back to a healthier balance. Because inflammation takes time to settle, methotrexate works gradually.

Although methotrexate was originally developed many years ago as a cancer medicine, the dose used in myositis is much lower and works in a completely different way.

Uses

Used in myositis, rheumatoid arthritis, and other autoimmune diseases.

How is methotrexate taken?

Once a week ONLY. It may be given as tablets or as an injection under the skin, like insulin.

No relation to any food or timing. It can be taken at any time of the day. It can be mixed with certain food substances that are cool or at room temperature — such as honey, vanilla ice cream, or cold coffee — to decrease associated anticipatory nausea.

Why do I need folic acid?

Your doctor will usually prescribe folic acid along with methotrexate. Methotrexate can interfere with the body's use of folate (a vitamin important for healthy cells).

Folic acid helps reduce side effects such as:

• Mouth ulcers
• Nausea
• Stomach upset
• Hair thinning
• Tiredness

Common side effects

Many people tolerate methotrexate well. Some common side effects include nausea, vomiting, reduced appetite, mild stomach upset, mouth ulcers, headache, and fatigue after the weekly dose.

These symptoms are often manageable. Taking the dose in the evening, after meals, having coffee or dark chocolate after the dose, or taking medicines to help curb the nausea can help.

Why are blood tests necessary?

Methotrexate can occasionally affect blood counts, liver function, and kidney function. Regular blood tests help detect side effects early.

• Complete blood count
• Liver function tests
• Kidney function tests
• Muscle enzymes

Missed dose

Take it within 1–2 days of remembering it and make that your day thereafter. Do not skip for the whole week.

If you develop infection or chickenpox exposure

If you develop high fever, a significant infection, hospital admission, or chickenpox exposure, contact your healthcare team. You may be advised to temporarily hold methotrexate.

Alcohol, pregnancy, and vaccines

Because methotrexate can affect the liver, excessive alcohol intake may increase risk. Discuss alcohol use with your doctor.

Pregnancy should be avoided while taking methotrexate. Please discuss pregnancy planning, contraception, and breastfeeding with your doctor.

Inactivated vaccines are generally safe and flu vaccination is encouraged. Some live vaccines may need special planning.