Feeling unwell is something we all experience at some point, and finding the right words to describe illness—whether physical or emotional—can make communication more empathetic, warm, and human. Idioms related to being sick help us express discomfort, exhaustion, or recovery in a way that feels natural and thoughtful, rather than overly clinical.
In this article, I’ll share 25 commonly used idioms for sick, explained clearly and used in context. As someone who has worked with language learners and writers for years, I’ve seen how idioms add emotional depth and authenticity to everyday communication. These expressions are especially useful in conversations, writing, and even professional settings when you want to sound caring and relatable.
1. Under the weather
Meaning: Feeling slightly ill or unwell.
Sentence: I’ve been under the weather since yesterday, so I stayed home.
Best use: Casual conversations when illness isn’t severe.
Other ways to say: Feeling off, not feeling well, a bit sick.
2. Feeling run-down
Meaning: Extremely tired and lacking energy due to illness or stress.
Sentence: After weeks of work pressure, I’m completely run-down.
Best use: Describing fatigue-related sickness.
Other ways to say: Exhausted, worn out, drained.
3. Sick as a dog
Meaning: Very ill.
Sentence: I was sick as a dog all night with food poisoning.
Best use: Informal emphasis on severe sickness.
Other ways to say: Extremely sick, terribly ill.
4. Out of sorts
Meaning: Feeling slightly unwell or emotionally off.
Sentence: She seemed out of sorts during the meeting today.
Best use: Mild illness or emotional discomfort.
Other ways to say: Not yourself, uneasy.
5. Under the knife
Meaning: Going through surgery.
Sentence: He’ll be under the knife next week for a minor procedure.
Best use: Talking about medical treatment.
Other ways to say: Having surgery, being operated on.
6. On the mend
Meaning: Recovering after an illness.
Sentence: Thankfully, my father is finally on the mend.
Best use: Positive updates about health.
Other ways to say: Recovering, healing.
7. Feeling blue
Meaning: Emotionally unwell or sad.
Sentence: Being sick for weeks made me feel blue.
Best use: Mental or emotional health contexts.
Other ways to say: Sad, low, depressed.
8. Down with something
Meaning: Currently sick with an illness.
Sentence: She’s down with the flu this week.
Best use: Casual explanations of illness.
Other ways to say: Sick with, suffering from.
9. At death’s door
Meaning: Extremely ill, close to collapse.
Sentence: He looked at death’s door before treatment began.
Best use: Dramatic emphasis (use carefully).
Other ways to say: Critically ill, gravely sick.
10. Not firing on all cylinders
Meaning: Not functioning properly due to illness.
Sentence: I came to work, but I’m clearly not firing on all cylinders.
Best use: Work or productivity-related illness.
Other ways to say: Off your game, unfocused.
11. Green around the gills
Meaning: Looking nauseous or sick.
Sentence: He turned green around the gills after the ride.
Best use: Visual descriptions of sickness.
Other ways to say: Pale, nauseous.
12. Laid up
Meaning: Confined to bed due to illness.
Sentence: I was laid up for a week with a fever.
Best use: Short-term illness descriptions.
Other ways to say: Bedridden, resting.
13. Off color
Meaning: Slightly ill or looking unwell.
Sentence: You look a bit off color today.
Best use: Polite concern.
Other ways to say: Unwell, pale.
14. Fighting fit (opposite context)
Meaning: Fully healthy again.
Sentence: After rest, she’s back to being fighting fit.
Best use: Recovery updates.
Other ways to say: Healthy, strong.
15. Catch a bug
Meaning: Get sick with an illness.
Sentence: I must have caught a bug while traveling.
Best use: Informal illness explanation.
Other ways to say: Get sick, fall ill.
16. Run a fever
Meaning: Have an elevated body temperature.
Sentence: He’s running a fever, so he stayed home.
Best use: Medical or family conversations.
Other ways to say: Have a temperature.
17. Feel lousy
Meaning: Feel very unwell.
Sentence: I felt lousy all morning.
Best use: Casual daily language.
Other ways to say: Feel awful, terrible.
18. Under the care of
Meaning: Being treated by a doctor.
Sentence: She’s under the care of a specialist.
Best use: Professional or formal tone.
Other ways to say: Being treated by.
19. Back on your feet
Meaning: Recovered and active again.
Sentence: It’s good to see you back on your feet.
Best use: Encouraging recovery messages.
Other ways to say: Recovered, active again.
20. Take a turn for the worse
Meaning: Health suddenly declines.
Sentence: His condition took a turn for the worse overnight.
Best use: Serious health updates.
Other ways to say: Deteriorated.
21. Under the doctor’s orders
Meaning: Following medical advice.
Sentence: I’m resting under the doctor’s orders.
Best use: Explaining restrictions.
Other ways to say: Advised by a doctor.
22. Feeling peaky
Meaning: Slightly ill or weak.
Sentence: I’ve been feeling peaky all day.
Best use: Mild sickness.
Other ways to say: Off, unwell.
23. A clean bill of health
Meaning: Declared healthy by a doctor.
Sentence: I finally got a clean bill of health.
Best use: Medical results.
Other ways to say: Fully healthy.
24. Worn to a frazzle
Meaning: Exhausted due to illness or stress.
Sentence: The flu left me worn to a frazzle.
Best use: Stress-related illness.
Other ways to say: Burnt out, exhausted.
25. On your last legs
Meaning: Extremely weak or exhausted.
Sentence: By evening, I was on my last legs.
Best use: Physical exhaustion from sickness.
Other ways to say: Nearly done, worn out.
FAQs
1. Why are idioms for sick important in communication?
They add empathy, clarity, and emotional connection, making conversations feel more human.
2. Can idioms for sick be used in professional writing?
Yes, when used carefully, especially milder idioms like under the weather.
3. Are these idioms common in spoken English?
Absolutely. Many are used daily in casual and professional settings.
4. Do idioms help language learners sound natural?
Yes, idioms improve fluency and cultural understanding.
5. Should idioms be used in medical contexts?
For informal communication, yes—but formal medical writing should remain precise.
Conclusion
Using idioms for sick allows us to communicate illness with warmth, care, and understanding. Whether you’re checking on a loved one, explaining your health at work, or writing creatively, these expressions help you sound natural, thoughtful, and emotionally aware. From my experience, mastering such idioms not only improves language skills but also deepens human connection—something we all need, especially when health is involved.
Andrew Christopher is a passionate visionary who blends creativity with purpose to bring ideas to life. With a focus on innovation and integrity, he inspires growth and lasting impact.
