S’pore man suffers hair loss & mouth sores after skin rash treatment, dermatologist suspended for 14 months

Man sees dermatologist for rash, ends up in hospital after treatment causes drop in blood cells

A man who sought help for an itchy skin condition found himself hospitalised for 10 days following a rash treatment prescribed by a dermatologist.

After taking prescribed medication for his rash, the man developed painful mouth ulcers, facial swelling, skin discolouration, and severe hair loss.

He was later diagnosed with bone marrow suppression, according to the Singapore Medical Council’s (SMC) Disciplinary Tribunal document.

The dermatologist who prescribed the rash treatment has since been suspended for 14 months.

Man sees private clinic in Novena for itchy skin

According to the decision by the SMC Disciplinary Tribunal document, the ordeal began in April 2020, when the man visited Naaman Skin and Laser Centre in Novena to treat a persistent, itchy rash that had plagued him for eight months.

Dr Khoo Boo Peng, the attending dermatologist, diagnosed him with nodular prurigo, a skin condition where itchy, hard lumps form.

He first prescribed a steroid injection, along with two immune-suppressing drugs, methotrexate and ciclosporin.

The man responded well, and Dr Khoo eventually stopped the medication.

Cheaper drug prescribed to save patient money

But when the rash returned a month later, Sr Khoo made a risky decision: he switched the medication to azathioprine and prednisolone.

Prednisolone is a steroid that reduces inflammation. Azathioprine is a strong immunosuppressant known to carry serious side effects if the patient is unable to metabolise it properly.

Yet, no testing was done to confirm if it was safe for the man.

Dr Khoo later told the tribunal that he chose azathioprine because it was cheaper than the earlier medication, and he wanted to save the patient money.

About two weeks after starting the new medication, the man began to experience troubling symptoms, the Disciplinary Tribunal document read.

He emailed Dr Khoo to say that he was suffering:

• swelling below his face
• darkened skin
• painful blisters around his lips
• mouth sores that made it hard to eat
• sudden, heavy hair loss

Dr Khoo replied that these were likely common and temporary side effects of the steroid prednisolone and told the patient to continue with the medication.

Eventually, he brought the man’s follow-up appointment forward and advised stopping prednisolone.

But by then, the patient’s condition had worsened.

Patient hospitalised, diagnosed with bone marrow suppression

On 2 July 2020, after a series of email exchanges about his other symptoms, the man sent a distressing email to Dr Khoo with photos of his hair loss.

“This is the amount of hair I lost this morning. Never happened before. Pls advise what to do with the steroid. It is killing me,” he wrote.

“I want to stop but scare of the withdrawal symptoms also [sic].”

He then rushed to Dr Khoo’s clinic, where the doctor finally admitted the symptoms might be due to azathioprine.

Two days later, the man was admitted to Mount Elizabeth Novena Hospital, where he was hospitalised for 10 days.

He was diagnosed with bone marrow suppression, a dangerous condition that affects the body’s ability to produce blood cells.

Tests confirmed the man’s body could not metabolise azathioprine, meaning the drug had been toxic to him from the start.

Doctor suspended for unsafe prescription & poor monitoring

Following the incident, the man filed a complaint with the SMC.

The Disciplinary Tribunal found Dr Khoo guilty of two charges of professional misconduct:

• prescribing azathioprine without first ensuring it was safe for the patient
• failing to closely monitor and respond to the patient’s side effects after starting the medication

While Dr Khoo said he was unaware that a genetic test should have been done before prescribing azathioprine, the tribunal said he still had a duty to rule out that risk.

Despite having over 30 years of experience in the medical field and glowing testimonials from six fellow doctors, the tribunal found the breaches too serious to ignore.

Dr Khoo was initially handed a 23-month suspension, but this was reduced to 14 months due to the lengthy time taken for the case to conclude.

As of 5 Aug 2025, his profile remains live on the Naaman Skin and Laser Centre website.

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