Grammar fix
serious illness
bad illness
An illness that is severe, dangerous, or could have major effects on your health.
collocationB1common
Hear it in context
Notice where the phrase sounds natural.
- After being diagnosed with a serious illness, she had to spend several weeks in the hospital.health
- If a family member has a serious illness, it can affect everyone’s daily routine and emotional well-being.IELTS speaking
Fix the pattern
Pattern: serious illness (noun phrase); have/suffer from/develop a serious illness
WrongShe has a heavy illness.
RightShe has a serious illness.
Illnesses are 'serious', not 'heavy' (heavy is about weight).
Patternserious illness (noun phrase); have/suffer from/develop a serious illness
Use it right
Choose the version that sounds natural in speech.
'A serious illness' is the everyday phrase; 'a grave medical condition' is clinical/report-speak.
Build natural chunks
Words that usually travel with it.
a serious illnesssuffer fromdeveloprecover fromlife-threatening
Don't confuse it
Not used for small or minor health problems like a headache or a cold.