What Is a Morbilliform Rash?
A morbilliform rash is any rash that looks a lot like measles. The word “morbilliform” means measles-like.
Sometimes dermatologists call them morbilliform eruptions. Many viral illnesses can cause this type of rash. But kids and adults also can get morbilliform rashes after taking a new medicine. When they happen from drugs, they’re called “morbilliform drug eruptions.”
How Common Is It?
It’s hard to say exactly how common these rashes are since they have so many different causes. Many people get morbilliform rashes after starting a new drug for the first time. This happens with about 2 in every 100 new prescriptions. Morbilliform rashes are by far the most common type people get from taking medicines. About 95% of drug-related rashes are morbilliform rashes.
You’re more likely to have this happen if you’ve had a rash after starting a new medicine before or if other people in your family have had this happen to them. It’s also more likely if you have a viral infection, such as Epstein-Barr virus or herpesvirus, or are taking multiple medicines at once. A weakened immune system from HIV, cystic fibrosis, or an autoimmune condition also makes it more likely.
Morbilliform rashes also come up often when you have a viral illness. They’re common in kids but can happen in adults, too. For example, one study found that most adults who had any skin symptoms with COVID-19 got a morbilliform rash.
Morbilliform Rash Causes
Many things can cause a morbilliform rash. If you’ve recently started a new medicine, your measles-like rash could be caused by it. Medicines that often cause these rashes include:
- Penicillins
- Sulfonamides
- Thiazides
- Sulfonylureas
- NSAIDS
- Anti-seizure medicines
These rashes can happen with many viral infections, including those caused by:
- Enteroviruses
- Adenoviruses
- Epstein-Barr virus
- Cytomegalovirus
- Herpesvirus
- Parvovirus
You can also get a morbilliform rash with respiratory illnesses, such as:
- Influenza B
- Pneumonia
- COVID-19
Especially if you’ve traveled recently, your doctor might consider the possibility that your rash is caused by an arbovirus. These viruses are spread by mosquitoes or ticks and include:
- Zika
- Dengue
- Chikungunya
- Brucellosis
- Leptospirosis
- Rickettsial disease or Rocky Mountain spotted fever (RMSF)
Other medical conditions can cause a morbilliform rash. For example, you may get this type of rash with Kawasaki disease or a connective tissue disease. They also can happen in people with graft-versus-host disease (GVHD). GVHD is a condition that can arise after a bone marrow or other organ transplant.
Could My Rash Be Measles?
Yes, measles is also a possible cause of your rash. This is much more likely if you haven’t been vaccinated against measles. While measles had been eliminated for almost 20 years in the U.S., measles outbreaks still happen in places around the world.
More cases are happening in the U.S., too. There were 97 cases of measles and seven outbreaks in the U.S. in early 2024. Those cases happened in 18 states. Most of the cases were in kids younger than 5. But older kids, teens, and adults also have had measles in the U.S. recently.
Measles is one of the most contagious of all diseases. A single person with measles can easily spread it to other people who don’t have immunity against measles. If you have a morbilliform rash and think you or your child could have measles, see a doctor right away.
Morbilliform Rash Symptoms
A morbilliform rash often will start on your chest and spread to your arms, legs, and neck. You’ll usually see the rash on both sides of your body.
You’ll have flat pink or red spots on your skin. They may merge together and could get bumpy as your rash spreads. Your rash may be harder to see if your skin tone is darker.
Your rash may itch. You also could have a fever along with your skin symptoms.
Morbilliform Rash Diagnosis
A dermatologist can easily tell if you have a morbilliform rash. But to diagnose and treat it, they’ll need to figure out the underlying cause. Your doctor will give you a physical exam and ask you lots of questions about your medical history. They’ll also want to know what medicines, if any, you’re taking and whether you’re up-to-date on your vaccines.
Let your doctor know if you’ve:
- Been in contact with anyone who is sick
- Traveled recently
- Been exposed to illnesses in your community
- Taken any new medications
- Had any reactions to drugs or foods in the past
- Got any infections, metabolic, or immune disorders
If your doctor suspects you may have a viral illness, they may order tests to see which one. If your rash is related to medicine you’re taking, your doctor will want to know:
- How long ago you started taking it
- How often you take it
- Whether you’re taking other medicines, too
- Whether you’ve noticed the rash getting better and then worse after taking your medicine again
If your morbilliform rash doesn’t go away or is severe, your doctor may order more tests, including:
- Biopsy
- Blood tests
- Antibody tests
- Cultures to look for infection
- Urine test
- Stool test
- Skin prick or patch testing for allergies
Morbilliform Rash Treatment
Your treatment will depend on what’s causing your rash. Morbilliform rashes with viral illnesses may go away on their own as you get better. Follow your doctor’s advice about treating any related illness you have.
If a drug is causing your rash, you should stop taking it if you can. Talk to your doctor about what to do if you need the medicine and there isn’t another option. You should never stop taking medicine you need without talking to your doctor first.
Treatment for the rash may include:
- Monitoring
- Topical steroids
- Wet wraps if your skin is very red and irritated
- Antihistamines, but they don’t usually help a lot
Morbilliform Rash Complications
Your rash isn’t likely to come with long-term complications. Most rashes related to drugs are mild. They also will go away if you stop taking the medicine. It might take a week or two for the rash to completely go away.
If your rash is related to a viral illness or another medical condition, the important thing is to treat the underlying cause. In some cases, a morbilliform rash may be a sign that an infection you have is more severe.
Some illnesses that can lead to this type of rash also may come with serious complications. For example, while rare, measles can lead to serious problems, including:
- Pneumonia
- Meningitis
- Blindness
- Seizures
When to See a Doctor
If you have a morbilliform rash that is a concern or isn’t going away, it’s a good idea to see a doctor to find out what’s causing it. While the rash itself may not cause serious problems, you may have a contagious illness or another condition that needs treatment.
Takeaways
Many viruses and medicines can cause a morbilliform rash that looks like measles but isn’t. Many times the rash will be mild and go away on its own. But it’s a good idea to figure out what’s causing your rash so you can treat the underlying problem or avoid the medicine or other trigger that’s causing it. If it’s possible you or your child could have measles, you need to see a doctor right away.
Morbilliform Rash FAQs
Can COVID cause morbilliform rash?
Yes, morbilliform rashes do sometimes happen when people have COVID. It’s more likely when your illness is more severe.
Is morbilliform rash an allergic reaction?
It depends. If an illness is causing it, it’s not an allergy. But morbilliform drug eruptions are a type of allergic reaction to medicines.
What is nonpruritic morbilliform rash?
“Pruritic” means itchy. If your rash is nonpruritic, that means it doesn’t itch.
Which drugs cause a morbilliform rash?
Many medicines can cause a morbilliform rash. They’re especially common with antibiotics.
