Overview

Diagnosis

Multisystem inflammatory syndrome in children is diagnosed based on a child’s symptoms and by ruling out other conditions that cause similar signs and inflammation. There is no single test for MIS-C, so healthcare professionals use a combination of clinical evaluation and laboratory testing.

Providers start by checking for an active COVID-19 infection. This is done by testing samples taken from the nose or the back of the throat. Blood tests are also used to rule out other inflammatory conditions such as Kawasaki disease, sepsis, or toxic shock syndrome.

Many children with MIS-C do not have an active COVID-19 infection at the time of diagnosis. Evidence of a past infection may be found through antibody testing, especially in children who had COVID-19 without symptoms. A history of COVID-19 infection among close contacts is also considered. In most cases, MIS-C develops within about two months of exposure to the virus that causes COVID-19.

To look for inflammation and other signs of MIS-C, providers may order several tests, including:

  • Blood and urine tests to measure inflammatory markers and organ function

  • Imaging tests such as chest X-rays, echocardiograms, abdominal ultrasound, or CT scans

  • Additional tests based on the child’s symptoms and which organs may be involved

These tests also help assess the severity of illness and guide treatment decisions.

Treatment

Children with MIS-C are treated in the hospital. Some require care in a pediatric intensive care unit. Treatment focuses on supportive care and reducing inflammation to protect vital organs from long-term damage. The treatment plan depends on how severe the symptoms are and which organs are affected.

Supportive care may include:

  • Fluids to treat dehydration

  • Oxygen to support breathing

  • Medicines to manage low blood pressure or support heart function

  • Use of a ventilator if breathing becomes severely impaired

  • Medicines such as aspirin or heparin to reduce the risk of blood clots

  • In very rare cases, extracorporeal membrane oxygenation, a machine that supports the heart and lungs

Treatment to reduce swelling and inflammation may include:

  • Antibiotics, especially while ruling out bacterial infections

  • Steroid therapy to reduce inflammation

  • Intravenous immunoglobulin, a blood product containing antibodies

  • Targeted therapies that lower high levels of inflammatory proteins called cytokines

There is no evidence that MIS-C itself is contagious. However, because a child may still have an active COVID-19 infection or another contagious illness, hospitals use infection control precautions during care.

Coping and support

Having a child critically ill with MIS-C can cause intense fear and anxiety. Because the condition is rare, families may feel isolated and unsure where to turn. Seeking support is important. This can include talking with family and friends or seeking help from a mental health professional. Your healthcare team can guide you to helpful resources and support services.

Preparing for your appointment

If your child shows emergency warning signs of MIS-C or appears severely ill, seek immediate medical care or call your local emergency number. Wear a mask to protect yourself and others.

If symptoms are mild, contact your child’s pediatrician or healthcare professional. The provider may evaluate your child or refer you to a specialist in infectious diseases.

What you can do
When scheduling the appointment, ask if there are any steps to take beforehand. Prepare information such as:

  • Your child’s symptoms and when they started

  • Important personal and family medical history

  • All medicines, vitamins, or supplements your child takes and their dosages

  • Recent group activities and dates

  • Questions you want to ask the healthcare professional

What to expect from your healthcare professional
You may be asked questions such as:

  • When the symptoms began and how severe they are

  • Whether your child has been tested for COVID-19

  • Possible exposure to someone with COVID-19

  • School attendance and recent group activities

  • Close contacts your child has had recently

Preparing in advance helps ensure all your concerns are addressed and that you understand the next steps in your child’s care.

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