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Fevers - Adults (18+ years)

Uh oh - the dreaded fever. It’s typically the first sign that something is going on and we rush around, grabbing all the medicine, preparing for the worst. Let’s start instead by congratulating our love’s (or our own - fever in adults is possible too!) immune system for doing its job and see how this plays out.

Fevers are caused by:

  • Illnesses (viral or bacterial)
  • Vaccinations
  • Overheating
  • Certain medications

What is a normal temperature for adults?

As a whole, our body temperature can range quite a bit throughout the day. It is lowest in the morning and highest in the late afternoon. A normal oral temperature reading can range from 95.8 to 99.9 (average of 97.6).

What is a high fever in adults?

For a loved one who is over 18 years old or if we’re concerned for ourselves, we can let the fever hit 103 F before we start to worry. You don’t even need to use medication until you see the 102-103 F mark or if you/your loved one are uncomfortable. Tylenol, ibuprofen, or aspirin are okay now that we’re all older than 18. But it is appropriate to see if the fever gets rid of the virus for you, too. Stay hydrated and make sure you aren’t overdressed or lying in a pile of blankets.

It is a common misconception that we must rotate Tylenol and ibuprofen but choosing just one is actually preferred. If the one you chose does not bring the fever down 2-3 degrees F within an hour, you may switch to the other medication. Our biggest concern is an accidental overdose - the less we give or take, the less we need to worry!

How to take temperature?

  • Temporal artery temperature, armpit (axillary) temperature, ear (tympanic) temperature, or by mouth (oral) temperature. Axillary is the least accurate and not recommended.

When to call the doctor?

  • Temperature goes higher than 103 F
  • Any fever present more than 3 days
  • Signs of lethargy
  • Signs of dehydration (dry mouth, no tears, no urinating >12 hrs)
  • Burning or pain with urination
  • Fever is accompanied by other symptoms that concern you (ear pain, vomiting, diarrhea)

When to go to the ER with fever?

  • Breathing difficulty
  • Confusion/Altered mental status
  • Stiff neck
  • Seizures
  • Fever >105 F

When is a fever dangerous?

A truly dangerous fever is >108 and is extremely rare, only seen in situations such as a heat wave. However, all fevers >105 should be investigated with a doctor as stated above. That said, less than 1% of fevers go higher than 105.

How to break a fever?

Rest, drink lots of fluids, and stay cool! Remember, that fever is on our side, fighting off our infections. So unless our fever hits 104 as discussed, there is no ‘breaking’ necessary.

Are fevers contagious?

Not necessarily. If a virus is the reason you or your child has a fever, then yes, it is considered contagious. But as discussed in the beginning here, vaccines or overdressing can also cause a fever - not contagious. And there are plenty of illnesses that may NOT cause a fever, so in general, don’t use fever as your guide on whether or not it can be spread to others.

Keep in mind that how you or your loved one is feeling is always more important than the actual number on your Kinsa thermometer. Follow your gut if you feel like something is wrong, but otherwise don’t be afraid to let our own immune system be the champion!

This content is intended for informational purposes only and should not be used as a substitute for professional medical advice, diagnosis or treatment from an appropriately qualified and licensed physician or other healthcare provider.

Learn where Kinsa’s medical information comes from.

Blake Wageman

Blake Wageman, RN, BSN has over 11 years of nursing under her belt, primarily focused on NICU babies and, just as importantly, their worried parents.