Feeling under the weather or sick as a dog? English uses many colorful expressions to talk about illness.
This guide explains the most common sick phrases idioms in simple language, with examples you’ll actually remember and use.
Whether you’re learning English or polishing your fluency, these idioms will help you sound natural in real conversations.
Under the Weather
Word-by-Word Meaning
Under = below
Weather = climate
Idiomatic / Figurative Meaning
Feeling slightly ill or unwell.
Example Sentences
- I’m feeling under the weather, so I stayed home today.
- She skipped the party because she was under the weather.
Common Error
❌ Using it for serious illness
✔ Best for mild sickness only
Usage Note
Very common in daily and professional English.
Sick as a Dog
Word-by-Word Meaning
Sick = ill
Dog = animal
Idiomatic / Figurative Meaning
Extremely sick, often with nausea or flu.
Example Sentences
- I was sick as a dog after eating street food.
- He’s been sick as a dog all week.
Common Error
❌ Thinking it’s insulting to dogs
✔ It’s just an expression
Usage Note
Informal, often spoken.
Run Down
Word-by-Word Meaning
Run = move
Down = low
Idiomatic / Figurative Meaning
Tired and weak due to stress or illness.
Example Sentences
- I feel really run down after work.
- She’s been run down lately.
Common Error
❌ Confusing with “run over”
✔ Totally different meaning
Usage Note
Common in health and lifestyle talk.
Come Down With Something
Word-by-Word Meaning
Come down = fall
Something = illness
Idiomatic / Figurative Meaning
To start getting sick.
Example Sentences
- I think I’m coming down with something.
- He came down with the flu yesterday.
Common Error
❌ Using it after full recovery
✔ Use at the start of illness
Usage Note
Very natural in conversation.
Out of Sorts
Word-by-Word Meaning
Out = not
Sorts = condition
Idiomatic / Figurative Meaning
Feeling unwell or mentally off.
Example Sentences
- I’m a bit out of sorts today.
- She’s been out of sorts all morning.
Common Error
❌ Using for physical injury
✔ Better for mood + health
Usage Note
Polite and mild expression.
On the Mend
Word-by-Word Meaning
Mend = repair
Idiomatic / Figurative Meaning
Recovering from illness.
Example Sentences
- He’s finally on the mend.
- I’m on the mend, thanks for asking.
Common Error
❌ Using it when still very sick
✔ Use during recovery
Usage Note
Positive and encouraging phrase.
Feel Like Death Warmed Up
Word-by-Word Meaning
Death = extreme state
Warmed up = reheated
Idiomatic / Figurative Meaning
Feeling extremely ill or exhausted.
Example Sentences
- I feel like death warmed up today.
- She looked like death warmed up.
Common Error
❌ Taking it literally
✔ It’s exaggeration
Usage Note
Informal, dramatic tone.
Not Feeling Yourself
Word-by-Word Meaning
Not = no
Yourself = normal self
Idiomatic / Figurative Meaning
Feeling slightly ill or off.
Example Sentences
- I’m not feeling myself today.
- He said he’s not feeling himself.
Common Error
❌ Using for personality change only
✔ Can mean health or mood
Usage Note
Very common in polite speech.
A Clean Bill of Health
Word-by-Word Meaning
Clean = clear
Bill = report
Health = condition
Idiomatic / Figurative Meaning
Confirmed to be healthy.
Example Sentences
- The doctor gave me a clean bill of health.
- She finally got a clean bill of health.
Common Error
❌ Using without medical check
✔ Needs confirmation
Usage Note
Formal and professional.
In Poor Health
Word-by-Word Meaning
Poor = bad
Health = condition
Idiomatic / Figurative Meaning
Frequently sick or weak.
Example Sentences
- He’s been in poor health lately.
- She retired due to poor health.
Common Error
❌ Using casually
✔ Sounds serious
Usage Note
Formal writing and speech.
Bedridden
Word-by-Word Meaning
Bed = sleeping place
Ridden = confined
Idiomatic / Figurative Meaning
Too sick to leave bed.
Example Sentences
- He’s been bedridden for days.
- She became bedridden after surgery.
Common Error
❌ Using for laziness
✔ Only for illness
Usage Note
Medical or serious tone.
Green Around the Gills
Word-by-Word Meaning
Green = pale
Gills = fish organs
Idiomatic / Figurative Meaning
Looking sick or nauseous.
Example Sentences
- You look green around the gills.
- He felt green around the gills.
Common Error
❌ Using for anger
✔ Only sickness
Usage Note
Informal and visual.
Ailing
Word-by-Word Meaning
Ail = suffer
Idiomatic / Figurative Meaning
Weak or unwell over time.
Example Sentences
- Her ailing health worried us.
- He took care of his ailing father.
Common Error
❌ Using for sudden illness
✔ Better for long-term
Usage Note
Formal and literary.
Knocked Out
Word-by-Word Meaning
Knocked = hit
Out = unconscious
Idiomatic / Figurative Meaning
Too sick or tired to function.
Example Sentences
- The flu knocked me out.
- She was knocked out all day.
Common Error
❌ Confusing with boxing
✔ Context matters
Usage Note
Informal speech.
In the Pink (of Health)
Word-by-Word Meaning
Pink = healthy color
Idiomatic / Figurative Meaning
Very healthy.
Example Sentences
- He’s in the pink of health.
- She feels in the pink again.
Common Error
❌ Using when sick
✔ Opposite meaning
Usage Note
Positive idiom.
Fighting Fit
Word-by-Word Meaning
Fighting = strong
Fit = healthy
Idiomatic / Figurative Meaning
Very healthy and energetic.
Example Sentences
- I’m back and fighting fit.
- She’s fighting fit now.
Common Error
❌ Using during illness
✔ After recovery
Usage Note
British English.
Feel Rough
Word-by-Word Meaning
Rough = uncomfortable
Idiomatic / Figurative Meaning
Feeling ill, tired, or hungover.
Example Sentences
- I feel rough today.
- He looked rough this morning.
Common Error
❌ Using for appearance only
✔ Health-related too
Usage Note
Very informal.
On Your Last Legs
Word-by-Word Meaning
Last = final
Legs = support
Idiomatic / Figurative Meaning
Very weak or exhausted.
Example Sentences
- I’m on my last legs.
- She was on her last legs after illness.
Common Error
❌ Using only for health
✔ Can mean tired too
Usage Note
Common idiom.
Catch a Bug
Word-by-Word Meaning
Catch = get
Bug = virus
Idiomatic / Figurative Meaning
Get sick from infection.
Example Sentences
- I caught a bug at work.
- He caught a stomach bug.
Common Error
❌ Thinking it’s literal
✔ It’s figurative
Usage Note
Very common spoken English.
At Death’s Door
Word-by-Word Meaning
Death = end
Door = entrance
Idiomatic / Figurative Meaning
Extremely ill, near death.
Example Sentences
- He was at death’s door.
- She looked at death’s door.
Common Error
❌ Using lightly
✔ Very serious meaning
Usage Note
Dramatic and strong.
FAQs About Sick Phrases Idioms
Q1: What are sick phrases idioms?
They are expressions used to describe illness or health figuratively, not literally.
Q2: Are sick idioms formal?
Some are informal (sick as a dog), while others are formal (clean bill of health).
Q3: Can I use these idioms in writing?
Yes, but choose formal ones for professional writing.
Q4: Do native speakers use these daily?
Yes, especially common ones like under the weather.
Conclusion
Mastering sick phrases idioms helps you understand real English, not just textbook sentences.
Start by learning 3–5 idioms, use them in daily conversation, and soon they’ll feel natural. Practice makes fluency!
“Angela Carter, author at SeekIdiom, explains English idioms with clear meanings, examples, and usage to help learners improve vocabulary and communication.”
