An attempt is being made at Holyrood to abolish prescription charges.
Unison wants drug companies to foot the bill for prescription costs
Scottish Socialist Party leader Colin Fox introduced a member's bill earlier this year, claiming the charges amount to a "tax on the sick".
The SSP wants MSPs to follow the Welsh Assembly, which will phase out charges by 2007.
The bill has moved to the health committee for discussion by MSPs and is being backed by the public services union Unison.
Unison health organiser Jim Devine said cost was a factor in 75,000 prescriptions not being picked up every year in Scotland.
About 91% of items dispensed in Scotland are already supplied free of charge.
Speaking on BBC Radio's Good Morning Scotland programme, Mr Devine said the Scottish Executive raised £43m every year through prescription charges and argued that the Scottish taxpayer should not be footing the bill.
He said too many people in Scotland were "storing up" health difficulties and not collecting the prescriptions they needed.
"They go into their chemist for a headache and buy painkillers," he went on.
"In the vast majority of cases, this will suffice. But in some other cases we have more serious problems and we store up difficulties.
"We store up difficulties in heart disease, strokes and people who have just been discharged from psychiatric hospital.
"If the choice is between eating and medication, they will choose eating."
Mr Devine said he was "astonished" by the Scottish Executive talking about the successes of efficient government when the country's drugs bill had reached nearly £1bn.
"According to Audit Scotland, that bill has doubled in real terms in seven years," he added.
"The health service has been a cash cow for drug companies and we believe we should learn lessons from other countries, sit down with the drug companies and ensure they pick up this tab."