ADVISING versus WARNING
You can use the word directly in sentences. Note that advising is stronger than suggesting/recommending, and not only is stronger language used but also stronger intonation.
2. Modal verbs ‘should’ or ‘ought to’, and ‘must’
‘should’ and ‘ought to’ have the same meaning and are used for very strong suggestions and advice.
This is so the listener is aware of a potential danger. But…
Warning! Try to avoid using “I warn you” when speaking to patients as it might seem aggressive or alarming and can make them more anxious.
Instead a warning is better done with indirect language such as: