The number of prescription items dispensed in Wales rose by 2.9m in the first year of free prescriptions, official figures show.
The number of dispensed items rose 5% from 59.1m in 2006/7 to 62m in 2007/8, the equivalent to 20 items per person.
The chief medical officer said it showed there was more preventative work and more cancer drugs prescribed.
But the Lib Dems said the figures proved their concerns of introducing free prescriptions.
The figures follow a five-year general trend of an increase in items dispensed.
The National Statistics on GP prescribing showed the net cost of the prescribed items was �584m - an increase of 1% on the previous year - and equivalent to �188.90 per head.
Wales' �3 prescription charge was abolished in April last year by the then Labour run assembly government.
Wales' Chief Medical Officer Dr Tony Jewell said: "We know that in Wales we have more people with long term illnesses than England.
"These figures reflect the fact that more preventative work is being undertaken, with GPs prescribing medicines which are helping people manage their chronic conditions and keeping them out of hospital, reducing the cost and pressure on the NHS.
"We are also issuing more medicines used to treat cancers, as cancer therapy has improved to a point where, for a number of patients, it is now a chronic condition, plus GPs are helping more patients with diabetes manage their condition under the new enhanced contract.
"The figures also show we are increasing access while reducing costs. The net cost per prescription item decreased from �9.80 to �9.42."
But Welsh Lib Dem health spokesperson Jenny Randerson said: "We warned the (assembly) government that giving free prescriptions for all would be disastrous and today's figures have vindicated our position.
The number of times dispensed rose by 2.9m, 5% rise
"A 5% increase (in items claimed) is disastrous when the (assembly) government is refusing to fund vital lifesaving drugs.
"The cost of this gimmick will be with Welsh patients for generations.
"While millionaires claim their free paracetamol, the health service will continue to be to stretched to provide life saving services."
Shadow Health Minister Jonathan Morgan, Tory AM, said the figures showed people in Wales were becoming increasingly reliant on prescribed medicine.
He said: "The number of prescriptions being issued for cardiovascular problems for example has risen by 141.5% and these are often for the largest, most expensive items.
"Rather than micro-managing the NHS, the assembly government should be looking at improving the nation's health.
"Only then, as we become a healthier country, will costs fall."
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