The phrase 'unless otherwise advised by your physician' is correct and can be used in written English. You can use it when you want to recommend or suggest that an individual should not do something unless their doctor has told them to do it. For example, you could say: "When taking prescription medication, follow the recommended dosage unless otherwise advised by your physician.".
Finish the full course of treatment, unless otherwise advised by your physician.
While tap water is your absolute best first choice, you can also consume tea, coffee, unflavored soda/mineral waters, diet drinks, artificially sweetened drink powders, low calorie drinks, etc., unless otherwise advised by your doctor.
Do not take more than the recommended dosage stated on the pain medicine bottle, unless otherwise advised by a physician.
Never soak in a tub or pool unless otherwise advised by the doctor.
Feed the turtle only every 3 to 4 days, unless otherwise advised for your specific species.
I think we should keep calm and carry on for now, unless otherwise advised.
Get at least 2.5 hours a week of moderate intensity exercise, such as walking, unless otherwise directed by your physician.
Being a terminologist, I care about word choice. Ludwig simply helps me pick the best words for any translation. Five stars!
Maria Pia Montoro
Terminologist and Q/A Analyst @ Translation Centre for the Bodies of the European Union