Roseola: High Fever Followed by Rash
The short answer
Roseola (also called sixth disease or exanthem subitum) is a very common viral illness caused by human herpesvirus 6 (HHV-6). It typically causes 3-5 days of high fever (often 103-105F) followed by a characteristic pink, flat or slightly raised rash that appears as the fever breaks. The rash itself is not itchy or painful and resolves within a few days. Roseola is most common between 6-24 months and is usually harmless, though the high fever can occasionally trigger febrile seizures.
Parents everywhere have the same worry. You are doing the right thing by looking into it.
By Age
What to expect by age
0-6 months
Roseola is uncommon before 6 months due to protective maternal antibodies. If your very young baby develops high fever, it is important to contact your pediatrician, as high fever in babies under 3 months especially can indicate serious bacterial infection and needs prompt evaluation. Any fever in a baby under 3 months warrants an immediate call to your doctor.
6-12 months
This is the peak age for roseola, and it is often the first significant illness a baby experiences. The fever can be quite high (103-105F) and last 3-5 days, which is understandably alarming. Your baby may be irritable, have mild nasal congestion, or be slightly less interested in eating. When the fever drops suddenly, a pink lacy rash appears on the trunk and spreads to the arms and face. The rash means the illness is essentially over. Manage fever with acetaminophen or ibuprofen (ibuprofen only after 6 months) and keep your baby well hydrated.
12-36 months
Roseola can still occur in this age group, though many children have already had it. The illness follows the same pattern: high fever followed by rash. Toddlers may be cranky and tired during the fever phase. By the time the rash appears, your child is typically feeling much better and is no longer contagious. Most children develop lifelong immunity after one infection. If your toddler has a febrile seizure during the high fever phase, it is frightening but typically not dangerous.
What Should You Do?
When to take action
- Your baby has high fever for 3-5 days followed by a pink rash as the fever breaks - this is the classic roseola pattern.
- The rash is flat or slightly raised, pink, and not itchy or painful.
- Your baby seems to feel better and is eating and drinking normally once the rash appears.
- The fever lasts longer than 5 days without a rash appearing.
- Your baby is drinking less than half their normal fluid intake during the fever.
- Your baby has had roseola before and seems to have it again (uncommon but possible with HHV-7).
- Your baby has a febrile seizure: stiffening, shaking, eyes rolling back, or loss of consciousness.
- Fever is above 104F and not responding to fever-reducing medication.
- Your baby is under 3 months with any fever, or shows signs of dehydration, extreme lethargy, or a stiff neck.
Sources
Related Resources
Trust your instincts. If something feels wrong, reach out to your pediatrician.
Worrying about your baby means you care. That is a good thing.
Related Medical Concerns
My Baby Has a Fever That Won't Go Away
Most fevers in babies and toddlers are caused by viral infections and resolve within 3-5 days. A fever that lasts longer than 3 days, returns after seeming to resolve, or is accompanied by worsening symptoms warrants medical evaluation. The most important thing is how your baby looks and acts - a child who is alert and drinking well with a fever is generally less concerning than one who is listless, regardless of the temperature.
Viral Rashes (Exanthems) in Babies: Types and Identification
Viral exanthems (rashes caused by viruses) are extremely common in babies and young children. They often appear during or after a viral illness and typically present as widespread pink or red spots or patches. Common viral rashes include roseola (rash after fever breaks), hand-foot-and-mouth disease, fifth disease (slapped cheek rash), and nonspecific viral rashes. Most viral rashes are harmless and resolve on their own within a few days to a week without treatment.
My Baby Had a Febrile Seizure
Febrile seizures are frightening to witness but are usually harmless. They affect about 1 in 25 children, typically between 6 months and 5 years, and almost never cause lasting harm. Most children who have one febrile seizure never have another, and they don't increase the risk of epilepsy significantly.
Hand, Foot, and Mouth Disease in Babies
Hand, foot, and mouth disease (HFMD) is a very common viral illness in babies and toddlers, especially during summer and fall. It causes small blisters or sores in the mouth and a spotted rash on the hands and feet. While it can make your child uncomfortable for a few days, it is not dangerous and resolves on its own within 7-10 days.
My Baby's Head Shape Looks Abnormal
Many babies develop temporary head shape irregularities that are completely normal. A cone-shaped head from vaginal delivery reshapes within days. Mild positional flattening (plagiocephaly) from sleeping on the back is very common and usually improves with repositioning and tummy time. However, head shape changes involving ridges, a persistently bulging fontanelle, or rapid head growth changes should be evaluated to rule out craniosynostosis.
Achondroplasia (Dwarfism) in Babies
Achondroplasia is the most common form of short-limbed dwarfism, affecting about 1 in 15,000 to 40,000 births. It is caused by a mutation in the FGFR3 gene and is usually apparent at birth with characteristic features including short limbs, a larger head, and a prominent forehead. Intelligence is normal. With monitoring for specific complications and supportive care, children with achondroplasia lead full, active, and independent lives.