When Should You Worry About a Rash?

When is it “just a rash,” and when is it something more serious? House Call Doctor elaborates on when to worry about a rash.

Rob Lamberts, MD ,
March 14, 2018
Episode #073

Children with a Rash: When to Worry

Fever and rash in kids may be the scariest one on this list, not because it’s usually something bad--it’s actually rarely bad--but because when it’s bad it can be really bad. The rule of thumb with kids is that sick kids look sick. A child who is playing happily usually doesn’t have a serious problem, but the child who is lethargic or is acting significantly out of character is more worrisome.

Meningococcus: The most scary infection of all, in my opinion, is a bacteria infection with an organism called meningococcusThere are three reasons this is scary:

  1. It kills half of the people infected 

  2. It kills them within hours

  3. It infects mainly healthy children, teens, and young adults.

The good news is that it is rare and there is an immunization to prevent it. We are currently giving this to middle-school aged kids or older, but it will likely shift to be given to infants in the future.

The classic sign of a meningococcus infection is a fever with a rapidly spreading rash that turns into purple bruising. I’ll put a picture in the transcript. If you see this, do not call your doctor; go to the emergency room immediately.

Toxic shock: Toxic shock is a condition that is caused by the toxins from staph or strep bacteria, and it can happen in both adults and children. It resembles a peeling sunburn and is associated fever and low blood pressure. Most people associate this with a prolonged or retained tampon use, but it can occur as a result of any skin infection caused by staph.

Herpes: Lastly, a blistering rash in an infant can signify an infection with the herpes virus--either gotten from mom in the birth process, or from adults with the herpes that causes cold sores. This infection is very dangerous in infants, and should prompt immediate attention.

When You Should Worry About a Rash

As far as general guidelines go, here are a few things that should prompt worry:

  1. Rash associated with high fever

  2. Rashes that are painful

  3. Rashes that spread rapidly

  4. Rashes in young infants

  5. Rashes associated with dizziness or fainting

  6. Rashes associated with lip swelling, throat swelling, and/or difficulty breathing

  7. Rashes that start immediately after taking a medication or eating a new food

These rules aren’t iron-clad, so as always, the simple fact that a rash worries you is an OK reason to seek medical attention.

Again, I will include a lot of valuable information at the bottom of this article, so make sure you check it out.

If you have topics that you want me to cover, send them to housecalldoctor@quickanddirtytips.com, or you can submit them to me on twitter or my Facebook page.

Let me once again remind you that this podcast is for informational purposes only. My goal is to add to your medical knowledge and translate some of the weird medical stuff you hear, so when you do go to your doctor, your visits will be more fruitful. I don’t intend to replace your doctor; he or she is the one you should always consult about your own medical condition.

Catch you next time! Stay Healthy!

Drugs that can cause Stevens-Johnson Reactions

Allopurinol (A drug used for Gout)

Amithiozone (anti-tubuculosis agent)



Barbituates (Seizure medication like Phenobarbital)

Carbamazepine (also known as Tegretal)

Cotrimoxazole or Trimethoprim-sulfamethoxazole (Sulfa Drug antibiotic also called Bactrim or Septra)

Hydantoins (Seizure medications, including the drug Dilantin or Phenytoin)

Lamotrigine (Seizure and psychiatric drug also called Lamictal)

Nevirapine (A drug used for HIV infections)

Piroxicam (An anti-inflammatory drug known as Feldene)

Sulfadiazine (A drug used for inflammatory bowel problems)

Sulfadoxine (A drug used to prevent malaria)

Sulfasalazine (Another anti-inflammatory Drug)

There are other common drugs (like Ibuprofen) that can rarely cause a Stevens-Johnson reaction, so just be aware that the presence of a rash with mouth blisters is a serious concern.

Rash image from Shutterstock


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