Drug wastage is costing the NHS millions
Action is needed to stop the "sheer madness" which is leading to millions of pounds being wasted on unused medicines, nurses say.
Delegates at the Royal College of Nursing conference in Liverpool said it was heart-breaking to see piles and piles of medicines going to waste.
They described cases where cupboards full of out-of-date medicines had been found in patients' homes.
They said people needed to be warned about the issue.
Black bin liners full of unopened boxes have been found while medicines are also thrown down the toilet or put in the bin.
Nurses proposed clearly labelling medicines with the details of how much they actually cost as well as handing out leaflets to patients about not getting repeat prescriptions if they were not using them.
They also suggested unused medicines that are returned to pharmacies could be repackaged and made available again - at the moment any returned drugs have to be disposed of.
About £300m of medicines are wasted each year in England, half of which is unnecessary, a Department of Health study found last year. If the rest of the UK is taken into account the figure is closer to £400m.
Christine Thomas, a community nurse in Swansea, described finding out-of-date medicines piled up in the houses of patients she cared for, saying the situation was "sheer madness".
She also gave the example of a obese patient who kept re-ordering slimming pills, but refused to take them because they ruined her appetite.
She added: "This is a significant problem. It needs significant commitment and motivation to resolve it."
John Hill, who described how he had seen a patient brought into to A&E with four carrier bags full of unused medicines, said: "We need to tighten up the safeguards. We need to stop all this waste."
And Susan Smith, a palliative care nurse, said: "It breaks my heart to see this kind of waste."
She said the key was for nurses and other NHS staff to regularly review the medicines patients were on.
But as well as being related to patients getting repeat prescriptions when they do not need them, medicines wastage is also caused by people not taking their drugs as they should.
Bj Waltho, a nurse from East Dorset, said this was worrying as it was leading to a large number of emergency admissions.
And she said in an era where the NHS was being asked to save money, tackling this issue could be a "real quick win".
A spokesman for the Department of Health said: "We are aware of these concerns and have been clear that the NHS must find ways of making savings to free up resources for frontline care.
"Reducing wasted prescriptions is a way of working more efficiently. Wastage of medicines in primary and community care in the NHS is not a systemic problem and the NHS is making greater efforts to reduce the amount of medicines wasted than ever before."