The patient only found out about the content of synbetamine a few days later when he visited another doctor, who advised him to stop taking it.

In the disciplinary hearing yesterday, Kwok chose not to testify before the council. His defence counsel said this was because Kwok could not recall exactly what he told the patient.

'Even if he did mention that some drugs contained steroids, he did not specifically mention that synbetamine contained it,' the lawyer said.

In mitigation, the lawyer said it was highly unlikely Kwok would repeat the mistake, since he had left private practice in 2008 to join a government medical centre.

He said since Kwok, who graduated in 2002, was still young, he had to bear the record of professional misconduct for the rest of his career. 'That is the biggest punishment already.' There was no evidence Chan had been harmed, he said.

The council gave Kwok credit for having a clear record and co-operating during the inquiry. It also ruled that the doctor 'prescribed a low dose of steroid for a short period'.

'This failure falls into a less serious offence compared to previous cases that have come before this council,' chairwoman Professor Felice Lieh Mak said.

The Medical Council has issued several warnings recently that doctors should only prescribe steroids in life-threatening cases.

The vice-president of the Society of Hospital Pharmacists of Hong Kong, William Chui Chun-ming, said steroids were like a 'magic drug' to treat inflammations and failures of the immune system. But taking high doses over a long period could cause cataracts, diabetes and glaucoma, among other side effects.

Children taking high dose of steroids could suffer retarded growth, he said.

Some doctors liked to prescribe steroids because they are powerful and can cure quickly, Chui said.

'Patients like to be cured as quickly as possible, so some doctors tend to prescribe high doses of steroids,' he said.