What are the side effects of Dimethyl fumarate?

Dimethyl fumarate, commonly known by its brand name Tecfidera, is a medication primarily used to treat relapsing forms of multiple sclerosis (MS). While it has demonstrated effectiveness in reducing the frequency of flare-ups and slowing the progression of physical disability, it is not without its side effects. Patients considering or already taking dimethyl fumarate should be aware of these potential adverse reactions to make informed decisions about their healthcare.

One of the most common side effects experienced by individuals taking dimethyl fumarate is flushing. This involves redness, warmth, itching, or a burning sensation in the skin, usually affecting the face and neck. Flushing typically occurs within the first month of treatment and may decrease over time. In some cases, taking the medication with food or using aspirin as advised by a healthcare provider can help mitigate this side effect.

Gastrointestinal issues are another frequently reported set of side effects. Patients may experience nausea, vomiting, diarrhea, abdominal pain, and indigestion. These symptoms generally appear early in the treatment course and may improve as the body adjusts to the medication. Nevertheless, persistent or severe gastrointestinal discomfort should be discussed with a healthcare provider to rule out other conditions or to consider alternative treatments.

Dimethyl fumarate can also affect the body's immune system, leading to a decreased white blood cell count. This condition, known as lymphopenia, can make patients more susceptible to infections. Regular blood tests are usually recommended to monitor white blood cell levels, especially during the first year of treatment. If a significant reduction in white blood cells is detected, the healthcare provider may adjust the dosage or discontinue the medication.

Another notable side effect is the potential for liver damage. Elevated liver enzymes in blood tests may indicate that dimethyl fumarate is affecting liver function. Symptoms of liver damage include jaundice (yellowing of the skin or eyes), dark urine, severe fatigue, and unexplained nausea or vomiting. Patients experiencing any of these symptoms should seek medical attention promptly.

Some individuals may also experience allergic reactions to dimethyl fumarate. Signs of an allergic reaction include rash, itching, swelling (particularly of the face, tongue, or throat), severe dizziness, and difficulty breathing. Immediate medical attention is crucial if any of these symptoms occur.

Less common but more severe side effects include Progressive Multifocal Leukoencephalopathy (PML), a rare and potentially fatal brain infection. Symptoms of PML include progressive weakness on one side of the body, vision problems, clumsiness, and changes in thinking, memory, and personality. While the risk of PML is low, it is a serious condition that requires immediate medical intervention.

Other potential side effects include itching, skin rash, and upper respiratory tract infections. Some patients have also reported a decrease in appetite, fatigue, and back pain. While these side effects are generally less severe, they can still impact the quality of life and may require medical attention if they become bothersome or persistent.

In summary, while dimethyl fumarate is an effective treatment for multiple sclerosis, it comes with a range of potential side effects. From common issues like flushing and gastrointestinal discomfort to more serious concerns like liver damage and PML, it is essential for patients to be vigilant and communicate openly with their healthcare providers. Regular monitoring and prompt reporting of any adverse symptoms can help manage these risks and ensure the best possible outcome from the treatment.