The thing about addiction is that there will always be someone looking to exploit a weakness or a loophole for a quick buck.

That is partly why the illegal sale of cough medicine containing codeine persists.

A lucrative black market supply of codeine cough medicine thrives because there is a demand, the Health Sciences Authority (HSA) has said.

To further deter pushers, HSA has raised fines for the first time in nearly 30 years.

Those who engage in the unlawful sale or import of codeine can now be fined up to $50,000 - five times the previous limit - and/or jailed for up to two years. The stiffer penalties took effect on Nov 1.

Codeine works well at suppressing coughs. But people can become addicted to the calming or euphoric effect that it induces.

The fine revision is a sign that the authorities are not letting up, and comes as the black market price of codeine cough medicine soars.

In 2015, the HSA said prices had nearly doubled. A 90ml bottle of codeine cough medicine costs around $30 on the black market. In 2010, a 110ml bottle was reportedly bought off the streets for $15.

The lure of bigger profits means the previous fine limit of $10,000 per charge might have had only a limited effect in discouraging the illegal trade.

Besides enforcement operations, the authorities monitor sales and release information and advisories to educate the public and healthcare professionals on the dangers of abusing codeine.

Things get murkier, however, when there are black sheep among healthcare professionals who profit from the illicit trade.

The public can make a difference in this fight by raising the alert when a friend, colleague or family member is involved because, over time, abuse of codeine can lead to organ damage and even death.

Raising fines alone may not be enough to stamp out the illegal supply chain. Nonetheless, it is a vital part of measures to contain the codeine scourge.