11 Reasons You Should Go to the Hospital for a Fever

When you or your child comes down with a fever, it’s natural to be a little worried. Most of the time, you can treat fevers at home and notice improvement in a couple of days. But how can you know if your fever is a sign of something more serious? Let’s review the signs that you are too ill to be at home and may need to visit the emergency room (ER) for a fever.

What is a fever?

Fever is an elevated body temperature that’s usually related to being sick. Fever is one of your body’s defenses against disease. Your immune system works best when your body temperature is higher than normal.

Interestingly, medical experts have trouble agreeing on what temperature defines a fever. That’s partly because it’s normal to have variations in body temperature throughout the day. The average normal body temperature is 98.6°F (37°C), with a range from 97.7°F to 99.5°F (36.5°C to 37.5°C). The CDC defines fever as any temperature over 100.4°F (38°C). 

When should you go to the hospital for a fever?

Most fevers are the result of your body fighting an infection and are usually nothing to worry about. When you get better from whatever virus or bacteria was making you sick, your fever will go away as well. But every once in a while, a fever can signal something more concerning. 

These types of fevers usually require a visit to the ER.

1. Fever in a newborn

You should go to the ER right away if your newborn has a fever of 100.4°F (38°C) or higher. Keep in mind, the newborn period is any time between birth and 3 months of age. At this age, babies have immature immune systems, so they have a much harder time fighting off infections. As a result, newborns are susceptible to urinary tract infection (UTI) and meningitis (brain infection), and they can be serious or life-threatening. 

The American Academy of Pediatrics recommends that every newborn with a fever should have urine and blood tests checked immediately. Some newborns even need to get a lumbar puncture performed to make sure they don’t have an infection near the brain.

What about toddlers?

Once children are past the newborn stage, the rules change a bit. For toddlers (generally ages 1 to 3 years), a single fever isn’t always as concerning on its own. What matters more is how your child looks and acts. A toddler who is playful, alert, and drinking fluids can often be monitored at home, even with a higher temperature. But if the fever is 104°F (40°C) or higher, lasts more than a few days, or comes with red-flag symptoms like lethargy, breathing problems, or dehydration, it’s best to get urgent medical care.

2. Fever over 104°F

A temperature of 104°F (40°C) or higher in children or adults is generally considered a red flag and should be checked right away. That said, the actual number often matters less than how you or your child looks and feels. Fevers that come with worrisome symptoms — like seizures, confusion, intense pain, or trouble breathing — can be dangerous even if the thermometer reads lower.

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If you or your child has a fever over 104°F (40°C), this can be a sign of a severe bacterial infection and should be checked. Unlike viral infections that usually get better on their own, bacterial infections that cause a fever this high often need antibiotics to get better.

It’s always a good idea to get a very high fever checked out at the ER, so you know what’s causing your symptoms and can get a treatment plan in place quickly.

3. Fever with a seizure

A seizure that happens with a high fever is usually a result of febrile seizures. Febrile seizures are a relatively common diagnosis in children younger than 6 years. Sometimes, though, a fever associated with a seizure can be a sign of something more dangerous like meningitis or encephalitis. 

Regardless of the cause, any person who has a fever and then experiences a seizure should be evaluated in the ER right away. The medical team will stop the seizures safely and then make sure there’s no dangerous infection that’s causing the seizure.

4. Fever with trouble breathing

Always head to the hospital if you or your child has a fever and trouble breathing. In children, this usually shows up as noisy or congested breathing, or your baby is working harder to breathe. You might notice when you see their ribs pulling in with each breath, or see them taking frequent breaks during feeding to breathe. 

In adults, trouble breathing usually shows up as feeling short of breath and working harder than usual to breathe. You can sometimes see that the lips turn blue or gray. If you or your child has trouble breathing along with a fever, it could mean you have a serious respiratory infection that needs immediate treatment like antibiotics and oxygen therapy.

5. Fever with confusion and lethargy

If you have fever with confusion or lethargy, it’s important to get ER care right away. When an infection gets very severe, it can make you lethargic and confused. This only happens when the infection causing your fever has reached a dangerous point, and you need intensive medical therapy. 

If you notice your baby is more difficult to arouse or seems less playful or vigorous, this could be a sign for concern. Adults with fever and severe infection may develop delirium. Symptoms of delirium typically include:

• Unusual or abnormal behavior

• Excessive tiredness

• Confusion

• Hallucinations

• Paranoia

It’s also best to get checked out if you’re feeling excessively weak, very dizzy when you stand, or you feel like you can’t get out of bed.

6. Fever with dehydration

A fever with dehydration needs to be evaluated in the ER and treated. Fever can lead to dehydration in a few ways. Sweating and decreased fluid intake from fever can lead to symptoms of dehydration. And if there’s any extra fluid loss from diarrhea or vomiting, that can also make dehydration even worse.  

One way to tell if you’re dehydrated is to see if you’re making a normal amount of urine. If you or your child have a fever, are making less urine than usual, and are unable to drink much, you could have severe dehydration. 

If the healthcare team confirms that you’re dehydrated, they’ll likely give you fluids intravenously (with an IV). This will help quickly replace any fluids you’ve lost through fever.

7. Fever with severe headache or neck stiffness

Mild headaches are common with fever. But if the headache feels more severe or you’re experiencing significant neck stiffness (particularly when touching your chin to your chest), these could be signs of meningitis. Meningitis can be life-threatening. The best way to treat meningitis is to get emergency medical care right away. 

8. Fever with severe abdominal pain

If you have a fever and intense abdominal pain, you need to go to the hospital for an evaluation. These symptoms could indicate a possible infection in the abdomen. Some infections inside the abdomen — like appendicitis or diverticulitis — need treatment with antibiotics or surgery. 

There are many other possible causes for abdominal pain and fever. These can include:

• UTI or kidney infection

• Gastroenteritis 

• Ischemic colitis

• Pancreatitis

In the ER, the healthcare team will do a series of tests along with a physical exam to figure out the source of your symptoms. 

9. Fever with a rash

The combination of new rash and fever should prompt a visit to the ER — especially in adults. While many causes of rashes aren’t harmful, a few need attention. And even when the rash is a basic skin infection that you can treat at home, some skin infections also need treatment in the hospital.

Many viruses that are common among kids cause harmless rashes and fever. But examples of more concerning rashes include:

• Formation of large blisters

• Appears on the palms or soles

• Looks like a bull’s-eye or target

• Small, red, or purplish spots that look like tiny bruises underneath the skin (also called petechiae).  

10. Fever due to medication

Sometimes you can get a fever without having any infection at all. One reason people can get a fever without an infection is called serotonin syndrome. This happens when you take high doses of certain medications, or if you mix certain medications together. Common culprits are: 

• Monoamine oxidase inhibitors (MAOIs), like selegiline

• Selective serotonin reuptake inhibitors (SSRIs), like sertraline or fluoxetine

• Serotonin and norepinephrine reuptake inhibitors (SNRIs), like duloxetine or venlafaxine

• Certain herbal supplements, like St. John’s wort or ginseng

• Migraine medications like sumatriptan or zolmitriptan

• Nausea medications like ondansetron

In addition to fever, other symptoms of serotonin syndrome are:

• Sweating

• Shivering

• Tremor

• Rapid heartbeat

• Feeling anxious or restless

Serotonin syndrome can be life-threatening. If you suspect you have it, get medical care right away.

11. Fever and hyperthyroidism

You may need to visit the ER for fever if you have severe hyperthyroidism (an overactive thyroid gland). Hyperthyroidism is a common medical condition that healthcare professionals usually treat in the office. Sometimes, though, hyperthyroidism can become so severe that it’s actually life-threatening. 

Thyroid storm happens when thyroid hormone levels rapidly increase in the body, causing fever and other symptoms like:

• Racing heart

• Diarrhea

• Vomiting

• Agitation

There are many causes of thyroid storm, including:

• Suddenly stopping antithyroid medications, like methimazole or propylthiouracil

• Thyroid surgery

• Infection

• Trauma

• Stroke or traumatic brain injury

• Medications, like amiodarone

Thyroid storm is deadly in up to 25% of people who have it. If you think you’re experiencing thyroid storm, go to the ER immediately.

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Written by:

Farzon A. Nahvi, MD

Farzon Nahvi, MD, is an emergency medicine physician and author of “Code Gray: Death, Life, and Uncertainty in the ER.” He works at Concord Hospital in Concord, New Hampshire, and teaches at the Geisel School of Medicine at Dartmouth.

Edited by:

Karla Robinson, MD

Karla Robinson, MD, is a medical editor for GoodRx. She is a licensed, board-certified family physician with almost 20 years of experience in health through varied clinical, administrative, and educational roles.

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