Mefenamic Acid and DRESS Syndrome

Mefenamic Acid and DRESS Syndrome: What Parents Need to Know

Mefenamic acid is a common painkiller that belongs to the class of non-steroidal anti-inflammatory drugs (NSAIDs). It is used to treat various conditions, such as menstrual cramps, headaches, muscle and joint pain, and fever. It is also prescribed for children in some cases, especially for high fever.

However, mefenamic acid is not without risks. According to a recent drug safety alert issued by the Indian Pharmacopoeia Commission (IPC), mefenamic acid can cause a severe allergic reaction called Drug Reaction with Eosinophilia and Systemic Symptoms (DRESS) syndrome. This is a rare but potentially life-threatening condition that affects the skin and internal organs. It usually occurs within two to eight weeks after taking the drug.

What is DRESS syndrome?

DRESS syndrome is a hypersensitivity reaction that involves the following features:S

1. Skin rash, which may be widespread, itchy, and red. It can also cause blisters, peeling, and swelling.
2. Fever, which may be high and persistent.
3. Enlarged lymph nodes, which may be tender and palpable.
4. Eosinophilia, which is an increase in the number of a type of white blood cell called eosinophils. These cells are involved in allergic and inflammatory responses.
5. Organ involvement, which may affect the liver, kidneys, lungs, heart, or blood. This can cause symptoms such as jaundice, dark urine, abdominal pain, shortness of breath, chest pain, or anemia.

DRESS syndrome can be fatal if not diagnosed and treated promptly. The mortality rate is estimated to be around 10%.

What causes DRESS syndrome?

The exact mechanism of DRESS syndrome is not fully understood, but it is thought to involve a combination of genetic, immunological, and environmental factors. Some drugs are more likely to cause DRESS syndrome than others, and mefenamic acid is one of them. Other drugs that have been associated with DRESS syndrome include anticonvulsants, antibiotics, antivirals, and antifungals.

It is important to note that DRESS syndrome is not a dose-dependent reaction, meaning that it can occur even with a low dose or a short duration of exposure to the drug. It is also not predictable, meaning that it can occur even if the drug has been used before without any problems. Therefore, it is not possible to prevent DRESS syndrome by adjusting the dose or frequency of the drug.

How is DRESS syndrome diagnosed and treated?

DRESS syndrome is diagnosed based on the clinical features, laboratory tests, and history of drug exposure. There is no specific test for DRESS syndrome, but some tests that can help confirm the diagnosis include:

• Complete blood count (CBC), which can show eosinophilia and other abnormalities.

• Liver function tests (LFTs), which can show elevated liver enzymes and bilirubin.

• Renal function tests (RFTs), which can show impaired kidney function and proteinuria.

• Chest X-ray, which can show lung involvement.

• Biopsy, which can show characteristic histological changes in the skin or affected organs.

The treatment of DRESS syndrome involves the following steps:

• Discontinuation of the suspected drug, which is the most important and effective measure. The drug should be stopped immediately and never taken again.
• Supportive care, which may include fluids, electrolytes, oxygen, and blood transfusions as needed.
• Corticosteroids, which are anti-inflammatory drugs that can reduce the severity and duration of the reaction. They are usually given orally or intravenously, depending on the condition of the patient.
• Other drugs, which may be used to treat specific organ complications, such as antihistamines, antibiotics, antivirals, or immunosuppressants.

The recovery from DRESS syndrome can take weeks to months, depending on the extent of the damage and the response to treatment. Some patients may have residual or chronic effects, such as scarring, organ dysfunction, or autoimmune diseases³.

What are the alternatives to mefenamic acid?

If your child needs a painkiller or an antipyretic, there are other options that are safer and less likely to cause DRESS syndrome. Some of them are:

1. Paracetamol, which is effective for mild to moderate pain and fever. It has a good safety profile and is widely available. However, it should be used with caution in patients with liver disease or overdose risk.
2. Ibuprofen, which is another NSAID that can be used for pain and inflammation. It has a lower risk of DRESS syndrome than mefenamic acid, but it can still cause gastrointestinal, renal, and cardiovascular side effects. It should be avoided in patients with asthma, peptic ulcer, or bleeding disorders.
3. Aspirin, which is also an NSAID that can be used for pain and inflammation. It has a similar risk of DRESS syndrome as ibuprofen, but it can also cause Reye's syndrome, a rare but serious condition that affects the brain and liver. It should not be given to children under 16 years of age.

Before giving any medication to your child, you should always consult your doctor  and follow the instructions on the label. You should also monitor your child for any signs of adverse reactions and seek medical attention if they occur.

Conclusion

Mefenamic acid is a common painkiller that can cause a severe allergic reaction called DRESS syndrome in some children. This is a rare but potentially life-threatening condition that affects the skin and internal organs. It can occur even with a low dose or a short duration of exposure to the drug. The treatment involves stopping the drug, supportive care, and corticosteroids. The recovery can take weeks to months, and some patients may have long-term complications. Therefore, parents should be aware of the risks of mefenamic acid and consider safer alternatives for their children. If you have any questions or concerns about mefenamic acid or DRESS syndrome, you should consult your doctor.