The number of drug users arrested at checkpoints has steadily increased over the years, with 81 cases last year, nearly double the 49 cases in 2012.
In 2013, 47 Singaporeans and permanent residents (PR) tested positive for drug consumption during random checks at entry points including Changi Airport and Woodlands Checkpoint,
It was a slight drop from the 49 recorded in 2012. But Central Narcotics Bureau (CNB) figures show it has been on a steep climb since.
Lawyers tell The Straits Times that many of those caught are youth who tested positive after returning from trips to places such as Bali, Thailand and Europe.
A CNB spokesman said young people in Singapore, and indeed globally, are displaying liberal attitudes towards drugs, especially cannabis.
These attitudes can lead to tragic outcomes.
Early last month, a Singaporean undergraduate died after falling from a hotel room in Bali. He had reportedly consumed "magic mushrooms" - psilocybin mushrooms which have hallucinogenic effects - mixed with orange juice before expressing an urge to jump from the fifth-floor room, reported Indonesian media.
A CNB spokesman said: "Some Singaporeans think they can evade detection and prosecution by going overseas to consume drugs. They are mistaken. "
Lawyers said many of those caught claimed they were not aware of the law - that even if the drug is consumed overseas, Singaporeans and PRs can still be dealt with as if the offence is committed here.
A comprehensive list of controlled drugs is in the Misuse of Drugs Act.
Lawyer Amarick Gill said he now sees at least twice the number of clients caught for consuming drugs overseas, compared with two years ago. Many of them are above 18.
They include undergraduates, full-time national servicemen and young working adults.
He said: "They have the money to travel and some of them even organise 'drug trips' overseas with the intention to try drugs and have a good laugh. They think that as long as they wait a few days after taking the drugs, it will be gone from their system and they won't get caught."
Others picked up the drug habit while studying overseas and continued to use drugs when they returned, said lawyer Ray Louis, who recently had two clients who were arrested for trying to buy marijuana in Singapore.
Dr Lambert Low, an associate consultant at National Addictions Management Service, said: "The reasons for the use of drugs overseas were many, including the stress of staying alone abroad and adjusting to a new culture.
"The easy availability of drugs, the lack of supervision and the permissive attitudes of their peers towards drugs helped to push those individuals towards drug use, which they subsequently regretted and sought treatment for."
Dr Low shared details of a case involving John (not his real name), who became hooked on cannabis while studying abroad. A roommate introduced him to it.
John developed psychotic symptoms after one year of smoking cannabis, but has since stopped. He is recovering with the help of counselling, and parental and peer support. John's psychotic symptoms are also in remission, said Dr Low.
Lawyer Daniel Atticus Xu had a polytechnic student as a client. He tested positive for drugs and was arrested at Changi Airport after returning from a trip with his schoolmates. He is now behind bars.
Lawyer Josephus Tan said that besides getting caught for consumption, there is always the danger that one might be sold a "bad hit" overseas.
He said: "You never know what's in the drug; it might be laced with other substances which could be even more harmful to the body."
Tan Tam Mei