There are many risks associated with taking expired medicine and with not properly disposing of medication. JGI/Tom GrillWhen last did a headache have you reaching into your medicine cabinet – and finding a bottle of aspirin that expired three years ago? Did you take it anyway? And, if you decided instead to get rid of those out-of-date painkillers, how did you do it? If you chose to throw it in the garbage or flush it down the toilet, you’re far from alone: a 2020 research review found that “disposal of pharmaceuticals by garbage and sewer is still the most common method in many countries with the absence of the proper disposal of expired medications from the patient side”.The problem is that both using expired medication and disposing of it unsafely comes with significant health, economic and environmental risks.The Conversation Africa asked pharmacy professor Renier Coetzee, who is also the vice-president of the Pharmaceutical Society of South Africa, about the risks posed by using expired medication, and how to safely dispose of expired and surplus medicines.Why is it dangerous to take expired medication?Expiration dates for medicines are determined through stability testing. This involves assessing how long a medicine remains safe and effective under various storage conditions. Manufacturers typically provide conservative estimates of expiration dates to ensure a medicine’s quality and safety.Medications degrade over time. That means they may not work as intended once they reach and pass their expiry date. This is of particular concern with medicines like antibiotics: subtherapeutic doses (those which are too low to work properly and so do not fully treat the illness or infection) can contribute to antimicrobial resistance. Read more: Antibiotic resistance threatens to "undo a century of medical progress": 5 essential reads Antimicrobial resistance occurs when bacteria, viruses or fungi stop responding to medicines (like antibiotics). This makes infections harder to treat. And that, in turn, increases the risk of disease spread, severe illness and death. Reduced potency in chronic disease medications like insulin or heart medication is also a worry, since this can have serious health consequences.Some expired medications can break down into harmful compounds. One example is ciprofloxacin. This antibiotic is used mostly to treat infections in the urinary and upper and lower respiratory tracts. Studies have shown that it can degrade into toxic byproducts that may harm the kidneys (and be hazardous to the environment if not properly disposed of). Exposure to heat, humidity and light can accelerate the breakdown of active ingredients. This applies to both scheduled medicines, prescribed by a doctor, and over-the-counter medicines. Consider paracetamol, which anyone can buy for pain and fever. A year-old paracetamol tablet may not seem dangerous – but if it’s degraded, it could be less effective in treating pain or fever, leading to unintended consequences like delayed treatment or overuse in an attempt to achieve relief. If potency is reduced, users might take a higher dose than needed, increasing the risk of overdose or side effects.It’s not just tablets and capsules that expire. Liquid medications, such as cough syrups and eye drops, are particularly vulnerable to contamination once expired, as the preservatives they contain lose their potency. This increases the risk of bacterial growth, which could lead to infections.Expired medications left in the home, particularly in unmarked containers, also increase the risk of accidental ingestion, especially by children. While some expired medications may still retain potency, there is no guarantee of safety. Safe disposal is essential to prevent misuse and potential harm to both individuals and the environment.Can I throw expired or surplus medicine in the bin or flush it down the toilet?I strongly discourage it. So do professional bodies like the Pharmaceutical Society of South Africa and the South African Pharmacy Council. For starters, it’s bad for the environment. Medications discarded in household trash can leach active pharmaceutical ingredients into soil and groundwater, potentially contaminating sources of drinking water.Flushing medicines down the sink or toilet introduces these substances directly into sewage systems. They often bypass conventional wastewater treatment processes; in Cape Town, South Africa, for example, many wastewater facilities don’t perform tertiary treatments. That allows poorly treated effluents, chemical compounds and pharmaceutical pollution to enter aquatic ecosystems. That’s bad news for wildlife and can disrupt ecosystems. Read more: Marine life in a South African bay is full of chemical pollutants Trace amounts of pharmaceuticals in water supplies pose risks to human health, too. Such low concentrations are generally considered to pose minimal direct health risks to humans. But there are concerns about their potential impact on antimicrobial resistance and endocrine disruption. Endocrine disruption refers to the interference caused by certain chemicals which can mimic, block, or alter the human body’s natural hormones. The process can lead to various adverse health effects.What are the safest, most responsible disposal methods?The preferred method for disposing of unused or expired medications is through drug take-back programmes or authorised collection sites. These programmes are designed to provide a safe, convenient and responsible means for individuals to dispose of unused or expired medications. In South Africa, the South African Pharmacy Council mandates that only authorised personnel, such as pharmacists or designated officials, may dispose of medicines, and they must produce a certificate of destruction to be stored for at least five years. However, a study among healthcare professionals in the country revealed that only 23.5% participated in proper medicine destruction within their facilities. This, as well as similar research I conducted with some colleagues in Australia, indicates a need for improved education and practices regarding pharmaceutical waste disposal.In other African countries, formalised medication take-back programmes are less common. Safe disposal methods must be established and promoted across the continent. Read more: We found traces of drugs in a dam that supplies Nigeria's capital city If more formal options are unavailable, you could mix medications with unappealing substances (like used coffee grounds or cat litter) and seal the mixture in a plastic bag before throwing it away. This can help to prevent accidental ingestion by children or animals. It also keeps medications away from toilets or drains, thereby lessening water pollution and harm to aquatic life.However, this approach is less than ideal and should only be a last resort.Renier Coetzee is affiliated with TB Proof and Touching Nations.