How do we express the degree of a body's temperature from low to high when talking about illness?

Question

In everyday English, people usually use fever to talk about a very high temperature. If someone's temperature is just high, they say that someone has a temperature rather than has a fever: He stayed home from school because he had a temperature.

Your child's forehead feels a bit warm, according to dictionaries, it's not correct to say "you have a fever".

How do we express the degree of a body's temperature from low to high when talking about illness?

Can we say these to express the degree from low to high?

-you have a little temperature: I am not sure it's ok to say that because "temperature" is a countable noun and "little" doesn't go with countable nouns

-you have a bit of a temperature

-you have a high temperature

-you have a little fever: I am not sure it's ok to say that because "fever" is a countable noun and "little" doesn't go with countable nouns

-you have a bit of a fever

-you have a high fever

Answer 1

These examples are all fine and would be understood by most native speakers.

"You have a little temperature" is OK because in this case temperature is not countable, it's referring to the degree of fever. One can have a little temperature (fever) the same way one can have a little dirt on one's nose. You would not say you have "two fevers" unless you mean two separate occasions where you had a fever.

Another common expression is "running a fever."

Cathy was running a fever so we kept her home from school.

The text you quoted is not really correct about fever versus temperature and I disagree with the linked site. Fever can be and is used for both mild and high temperatures. It's easy to find examples.

When referring to a fever that is not high, you'll often hear the phrases "slight fever," "mild fever," or "low-grade fever." This is common usage, and not wrong at all.

Usually these mean a body temperature that's above normal, but below the threshold of concern, usually up to 101F or 38C.

The common term for a high fever is usually just high fever and usually means a fever that's high enough to be of serious medical concern, generally above 102 to 103 F (39-40C.)

Medically, a fever is defined as a temperature above 100.4F/38C, but normal body temperature varies per person, and the ranges differ for children versus adults. These are guidelines, not hard rules.

Answer 2

"You have a fever" is perfectly okay to use.

For instance, if you go to "https://medlineplus.gov/fever.html", which is the website of the U.S. National Library of Medicine, you will see various usages of the word fever, including "you have a fever".

As for the list of expressions you gave, it is okay to say "I have a temperature, I have a bit of a temperature" casually. But "in proper English" what you need to say is "I have a high temperature; I have a bit of a high temperature." or even better "I have an elevated temperature; I have a bit of elevated temperature."