SINGAPORE - Nine people suffered from serious skin reactions - such as blistering and skin peeling - after taking medicines meant to improve alertness and boost energy levels.
In a statement on March 10, the Health Sciences Authority (HSA) urged members of the public to not buy or take products that contain modafinil or armodafinil on their own.
Between February 2024 and February 2025, seven men and two women aged between 18 and 57 were hospitalised after consuming these medicines.
Modafinil and armodafinil are unregistered in Singapore, but can be obtained in some countries as prescription medicines for patients with specific medical conditions such as narcolepsy, said HSA.
Narcolepsy is a condition that impairs a person’s ability to sleep or stay awake.
The nine people had obtained the medicines from street peddlers in Geylang or friends, and consumed them without a doctor’s prescription and medical supervision.
“Some of them shared that they had taken these products to improve alertness or boost energy,” said HSA.
Six of the nine developed Stevens-Johnson syndrome (SJS), a life-threatening skin condition that causes blistering, severe peeling of the skin and mucous membranes.
In addition to these symptoms, one man in his 40s also had severe oral ulcers that left him unable to eat and speak for a few days, said HSA.
Three others suffered from toxic epidermal necrolysis, a more severe form of SJS that caused “painful blistering rashes and peeling of skin that spread across the entire body”, among other skin reactions, said the agency.
It added that one man in his 20s had “life-threatening blistering” that covered 60 per cent of his body, including his face, chest, genital areas, legs and soles of his feet.
“Most of the consumers are recovering and there were no mortalities.”
Both medicines need to be prescribed by doctors and used under strict medical supervision as they can cause life-threatening skin reactions such as SJS and TEN, said HSA.
They can also cause other serious reactions such as heart problems, hypertension, and psychiatric conditions such as anxiety, hallucinations or mania.
“Additionally, modafinil and armodafinil carry a potential risk of dependency due to their stimulant effects on the brain,” said HSA.
Although cases of SJS and TEN are rare, such conditions can be life-threatening and lead to widespread skin damage, said associate professor Lee Haur Yueh, a senior consultant at Singapore General Hospital’s department of dermatology.
In severe cases, SJS and TEN can lead to organ failure, said Prof Lee, who treated some of the hospitalised consumers.
“The fact that we are seeing a significant number of cases from armodafinil and modafinil suggests that the risk associated with these medicines is pretty high,” said Prof Lee.
“These medicines should only be taken when prescribed by a doctor, and with proper medical supervision to ensure patient safety.”
HSA also advised members of the public to not obtain or use both medicines from any illegal, unknown, unregistered or unreliable sources, as they could be harmful.
“Do not share or supply potent prescription medicines to your friends or relatives, even if their medical conditions may appear similar to yours,” said HSA.
“The medicines may not be suitable or safe for them, and their medical condition may need to be assessed first and managed by a doctor.”
Those found guilty of supplying and selling modafinil and armodafinil without HSA’s authorisation can be fined up to $50,000, jailed up to two years, or both.
Members of the public who have any information on the illegal sale and supply of these medicines can contact HSA’s enforcement branch.
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