Household medicine can become waste for numerous reasons. Non-adherence, early recovery, therapy changes or prescription and purchasing errors can all lead to medicine remaining unused or expiring in households. Estimates of the share of household medication becoming waste vary from 3% to as high as 50%. In France, it was estimated that households disposed of 17 600 tonnes of unused or expired medicine in 2018, equivalent to 260 g per capita.

Demographic, epidemiological and lifestyle changes such as an ageing and growing population, the rise of chronic health conditions, the availability of inexpensive generic treatments and changes in clinical practice have led to increased pharmaceutical prescription and usage in OECD countries. As a consequence, the amount of unused medicine that becomes waste is also increasing, which makes their environmentally sound management ever more important.

Medicines flushed via sinks and toilets enter sewage waters and risk leaking into freshwater systems. Conventional wastewater treatment plants are not designed to remove pharmaceuticals, resulting in emissions into waterbodies in unchanged or metabolised form. Depending on the removal efficiency of the conventional wastewater treatment plants, some pharmaceutical residues are removed to a limited extent and collected in the sewage sludge. These may still enter environmental systems, when sewage sludge is applied on land for agricultural use (“landspreading”) or composting, both common practices in most OECD countries.

Pharmaceuticals disposed of in municipal solid waste can also enter the environment. When mixed municipal solid waste is landfilled, pharmaceutical residues risk leaching into the environment if leachate is not collected and treated properly.

The implications of improper disposal of unused or expired medicine are threefold. First, certain pharmaceuticals have been proven to cause adverse effects to ecosystems when entering environmental systems, including increased mortality in aquatic species and changes to physiology, behaviour or reproduction. The discharge of antibiotics can also lead to mutations in animals and the development of antimicrobial resistant bacteria. Second, there is a possible public health risk of accidental or intentional misuse and poisoning if unused medicine is extracted from public or private waste bins. Third, unused pharmaceuticals represent wasted healthcare resources and economic losses.

Various policy interventions can be taken across the lifecycle including source-directed, user-orientated and waste management measures, to prevent medicine waste and reduce environmental leakage.

First, prevention measures such as improved disease prevention, personalised and precision medicine or better dimensioning of packaging sizes can help avoid pharmaceutical waste. A study in the Netherlands estimated that approximately 40% of pharmaceutical waste through unused or expired medicines could be prevented. Marketplaces for and redistribution of unused close-to-expiry date medicines can also improve the matching of supply and demand and prevent wastage. Resale and re-dispensing of unused medicines is still a niche, due to concerns regarding counterfeits, quality assurance and consequent legal restraints, but a number of initiatives exist.

Nevertheless, fully eliminating unused medicines is difficult. For instance, some patients may recover more rapidly than foreseen, change their treatment or not adhere to prescribed treatments. Patients may also preventively stock over-the-counter drugs, which expire before being completely utilised. Ensuring proper collection and disposal of these unused or expired medicines is thus indispensable.

Collection and disposal of unavoidable pharmaceutical waste needs to be customised to the national context and local challenges. Where there is a risk that medicine disposed in mixed waste can leach or be misused, separate collection is recommended to reduce environmental and public health impacts. Extended producer responsibility schemes have shown to be an effective approach to organise environmentally sound separate collection and treatment. The four OECD countries with highest collection ratios (i.e. France, Sweden, Portugal and Spain) have an extended producer responsibility scheme in place with full and harmonised national coverage and with collection points at pharmacies. Alternative approaches such as publicly financed take-back schemes can also be effective but do not implement the polluter pays principle.

Finally, limited awareness of consumers about proper disposal routes and drug take-back schemes weakens their impact in many countries. In Latvia, 60% of respondents admitted to not being aware of how to dispose of unused or expired medicine properly. A survey conducted in the Netherlands concluded that 17.5% were unaware that liquid medicines should not be flushed. In order to increase the awareness of citizens about proper disposal routes and/or the existence of drug take-back schemes, governments should develop, or mandate producer responsibility organisations to set up well-focused communication campaigns. In particular, liquids, ointments and creams tend to be discarded improperly, which highlights that further information campaigns or behavioural nudges would be beneficial in many countries.

Additional approaches that can also lead to increased awareness and behavioural change include: special instructions for appropriate disposal routes that appear on the outer packaging of medicinal products or in the information leaflet, nudges such as ‘challenges’ or ‘saving accounts’ to return medication to pharmacies or product ecolabelling to inform consumer choices. Awareness and informative tools for health professionals can also help to strengthen environmental considerations in prescription practices and disseminate the risk of inappropriate disposal routes among the population.