Better medicines management would reduce carbon emissions and could save the NHS in England more than £89m a year, the unit believes.

A total of 52% of respondents to the poll, by IPSOS Mori, would be very likely or likely to accept re-issued medicines, while 32% said they would not.

Sustainability unit director Dr David Pencheon said re-use of drugs had been dismissed in the past on the assumption patients would not agree. ‘In health we have always veered firmly on the side of caution and thrown away medicines. But now, as the economics of this behaviour is starting to stack up, we need to examine if that is appropriate. Do we need to look at changing the legislation?’

Dr Bill Beeby, chairman of the GPC prescribing sub-committee, said the safety considerations were more complex than was being acknowledged.

‘The amount of safety mechanisms needed for this would simply not be worth it for most low-cost medicines. It’s only really the high value medicines where it would benefit.’

He said packets would need to have mechanisms to show exposure to excessive heat.

'For example a patient may have an unopened box of medication but they may have stored it in a cupboard above the stove which could affect the stability of the drug. There’s no way we can currently know that.

‘But I can understand why people feel this is an area we should be focusing on to reduce wastage,’ he said.

The poll was commissioned alongside a report on NHS progress to date on embedding sustainability. It said the NHS was making progress on reducing emissions but not doing enough to prepare for predicted climate threats such as frequent and longer periods of hot and cold weather and flooding.