In 15 Seconds
- Standard way to say you have a fever in Japanese.
- Uses the verb 'deru' meaning the heat is emerging.
- Essential for medical visits or calling out of work.
Meaning
This is the most common way to say you have a fever. It describes the physical sensation of heat 'emerging' or 'coming out' from your body when you are sick.
Key Examples
3 of 6Calling out of work
すみません、熱が出たので今日はお休みします。
I'm sorry, I have a fever so I will take today off.
Texting a friend to cancel plans
ごめん！急に熱が出ちゃったから、今日行けない。
Sorry! A fever suddenly popped up, so I can't go today.
At the pharmacy
昨日の夜から高い熱が出ています。
I've had a high fever since last night.
Cultural Background
In Japan, the threshold for a 'fever' is often lower than in the West, with 37.0°C being a common cutoff for school or work. The phrase reflects a traditional view of illness where symptoms 'surface' from the body's internal state. During flu season, you will see 'Cooling Sheets' (like Netsusama-shi) sold everywhere to help the 'heat come out.'
The 37-Degree Rule
In Japan, 37.0°C is the magic number. If you tell a Japanese person your temp is 37.2, they will treat you like you're seriously ill!
Don't 'Have' It
Avoid saying 'Netsu o motte iru.' It sounds like you are physically holding a piece of heat in your hand.
In 15 Seconds
- Standard way to say you have a fever in Japanese.
- Uses the verb 'deru' meaning the heat is emerging.
- Essential for medical visits or calling out of work.
What It Means
In English, you 'have' a fever like it is a possession. In Japanese, you use the verb deru, which means 'to come out' or 'to emerge.' It feels like the heat is surfacing from inside you. It is the go-to phrase for any temperature above your normal baseline. Whether it is a mild sniffle or a full-blown flu, this phrase covers it all.
How To Use It
You will mostly use the past tense deta or the ongoing dete iru. If you just realized you are hot, say netsu ga deta. If you have been suffering all night, use netsu ga dete imasu. You can add adverbs like takai (high) to show how bad it is. Just remember that the 'heat' is the subject doing the action of 'coming out.'
When To Use It
Use this when calling your boss to skip work. Use it at the pharmacy when buying medicine. It is perfect for texting a friend to cancel dinner plans. You will also hear it constantly at the doctor's office. It is a very safe, standard expression for any medical situation. Even kids use it to get out of school!
When NOT To Use It
Do not use this for spicy food heat. That is karai. Do not use it for the weather being hot. That is atsui. Also, avoid it when talking about passion for a hobby. For that, Japanese people say netsu ga hairu (heat enters). If you say netsu ga deta during a date, they will think you are sick, not romantic!
Cultural Background
Japan has a very specific 'fever culture.' Many people carry digital thermometers in their bags. A temperature of 37.0°C (98.6°F) is often considered the 'danger zone' where you should stay home. In offices, showing up with a slight fever used to be seen as 'ganbaru' (trying hard). Nowadays, people are much more likely to tell you to go home immediately.
Common Variations
You will often hear netsu ga sagaru when the fever breaks. If the fever is stubborn, it is netsu ga hikanai. If you have a 'wisdom fever' from overthinking or stress, it is called chie-netsu. There is even a phrase for 'fever of unknown origin' called fumei-netsu. Japanese medical vocabulary is surprisingly descriptive!
Usage Notes
The phrase is neutral and can be used in almost any setting by changing the verb ending. Use `deta` for casual and `demashita` for formal situations.
The 37-Degree Rule
In Japan, 37.0°C is the magic number. If you tell a Japanese person your temp is 37.2, they will treat you like you're seriously ill!
Don't 'Have' It
Avoid saying 'Netsu o motte iru.' It sounds like you are physically holding a piece of heat in your hand.
Wisdom Fevers
The term 'Chie-netsu' (wisdom fever) is used for babies getting teeth or adults who get sick from thinking too hard. It's a great way to be self-deprecating!
Examples
6すみません、熱が出たので今日はお休みします。
I'm sorry, I have a fever so I will take today off.
A very standard and polite way to inform your boss.
ごめん！急に熱が出ちゃったから、今日行けない。
Sorry! A fever suddenly popped up, so I can't go today.
Uses the casual 'chatta' form to show regret and suddenness.
昨日の夜から高い熱が出ています。
I've had a high fever since last night.
Adding 'takai' (high) emphasizes the severity to the pharmacist.
子供が熱を出して、全然下がりません。
My child has a fever and it won't go down at all.
Shows concern using the 'te' form to connect the fever and the result.
テストが難しすぎて、知恵熱が出そうだよ。
The test was so hard, I think I'm getting a 'wisdom fever.'
Uses 'chie-netsu' humorously to mean your brain is overheating.
まだ熱が出てるの？何か買ってこようか？
Do you still have a fever? Should I go buy something for you?
Uses the continuous form 'dete iru' for an ongoing state.
Test Yourself
Choose the correct verb to complete the sentence: 'I have a fever.'
昨日から熱が___。
While 'arimasu' (to exist) is sometimes understood, 'demashita' (emerged) is the natural collocation for a fever.
How do you say you have a 'high' fever?
___熱が出ています。
In Japanese, fevers are 'high' (takai), not 'big' or 'strong'.
🎉 Score: /2
Visual Learning Aids
Formality of 'Netsu ga deru'
Used with friends: 'Netsu deta!'
熱出た！
Standard polite form: 'Netsu ga demashita.'
熱が出ました。
Humble/Polite for work: 'Netsu ga gozaimasu.' (Rare, usually just use neutral)
熱がございます。
When to say 'Netsu ga deru'
Doctor's Office
Explaining symptoms
Workplace
Calling in sick
Pharmacy
Buying medicine
Home
Telling family you feel sick
Practice Bank
2 exercises昨日から熱が___。
While 'arimasu' (to exist) is sometimes understood, 'demashita' (emerged) is the natural collocation for a fever.
___熱が出ています。
In Japanese, fevers are 'high' (takai), not 'big' or 'strong'.
🎉 Score: /2
Frequently Asked Questions
10 questionsYes, netsu ga arimasu is grammatically correct and means 'I have a fever.' However, netsu ga deru is much more common when describing the onset of the illness.
Use the word binetsu. You can say binetsu ga arimasu or binetsu ga demashita for a low-grade fever.
Yes, if you add the polite ending: netsu ga demashita. It is perfectly acceptable for professional communication.
The opposite is netsu ga sagaru, which means the fever is going down or has broken.
No, for passion use netsu ga hairu. Using deru only refers to physical sickness.
You can ask netsu ga aru no? (casual) or netsu ga arimasu ka? (polite).
It means the fever won't go away or won't subside, often used when you've been sick for several days.
Not really slang, but people often drop the particle: netsu deta. It sounds very natural and punchy in casual conversation.
It reflects the idea that the symptom is manifesting or appearing on the surface of the body.
Originally it meant a baby's fever during development, but now adults use it jokingly when they are stressed or overwhelmed: chie-netsu ga desou.
Related Phrases
熱を測る
to take one's temperature
熱が下がる
fever goes down
微熱
slight/low-grade fever
知恵熱
wisdom fever (stress-induced)
