How to tell if you have a fever without a thermometer

• You can tell if you have a fever without a thermometer by checking for a few common symptoms.
• The most common symptoms associated with a fever are feeling hot or flushed, chills, body aches, sweating, dehydration, and weakness.
• If you're experiencing one or more of these symptoms, and you feel warm to the touch, it's likely that you have a fever.

Fever occurs when the body's temperature rises above 100.4° F, usually because of an underlying infection or illness.

Thermometers can be used to measure a person's temperature, but it's possible to suspect a fever without a thermometer. That's because there are common symptoms associated with a fever - like body aches, chills, flushed skin, and sweating or dehydration.

Here's how to gauge the symptoms of a fever, along with your temperature, even if you don't have access to a thermometer.

How to tell if you have a fever without a thermometer

Knowing the symptoms that accompany a fever is the best way to determine whether you have one when you're not able to take your temperature.

For example, people with fever often experience:

• Body aches and weakness. Body aches, headaches, and weakness are very common in people with fevers. Aches often accompany viruses like the flu or common cold as a result of inflammation from the body's immune response to the virus.
• Chills. Many people with fever experience chills or shivering, even as their temperature is high. This is because the body is trying to raise your temperature to address the cause of the fever. People who are chilled because of fever will still feel hot to the touch, and they should dress in light layers.
• Flushing: Many people with fever experience flushing, or red cheeks. This happens when the body opens blood vessels - a process known as vasodilation - which increases blood flow to the skin and causes flushing.
• Sweating and dehydration. Many people with fever sweat, which is the body's attempt to regulate temperature and cool down, but it can be dangerous if you're not drinking enough water. "With high fevers, we can lose a significant amount of fluid through sweating," says Jordana Haber, MD. If you think you have a fever, watch for signs of dehydration, including dry mouth, excessive thirst, or confusion.

Feeling changes in your own temperature

If you're already experiencing these common symptoms of a fever, you can also gauge your own temperature based on how you feel.

"Feeling like you have fever is a pretty accurate way of knowing," says David Cutler, MD, chairman of the Santa Monica Family Physicians medical group. "If you feel hot or chilled, there's a pretty good chance you have a fever."

Fevers can make people feel hot or cold, Cutler says. You might feel and look flushed (with rosy skin) or shiver, both of which indicate that your body is trying to lower your temperature.

When trying to diagnose fever without a thermometer, people often touch their forehead. This won't work on yourself, since your entire body feels hot. However, having someone else touch your forehead can be an effective way to detect fever without a thermometer, says Haber, especially if you are experiencing those other symptoms.

It's most effective if someone touches their own forehead, then yours, in order to better gauge the differences in temperature. Of course, this practice isn't as efficient as using a thermometer to get a temperature readout.

"Diagnosing temperature by touch will give you a qualitative answer rather than a quantitative answer," Haber says.

When to seek medical attention for fever symptoms

Overall, it's more important to monitor fever symptoms and their severity, rather than the specific temperature someone has.

"It's not the height of the fever we're concerned about, it's the health of the patient," Cutler says.

Kids often run high fevers but act normal. In that case, they likely don't need medical attention, Cutler says. However, someone with severe symptoms - like significant confusion or trouble breathing - should seek medical attention even if they have a low fever.

Overall, people who have trouble breathing, a rash, or a fever higher than 104°F should contact their doctor. The CDC says that those who have a fever and a known exposure to someone with COVID-19 should also seek medical attention.

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