Out-of-date pills: warning to people that expired medicine can harm instead of help

Experts are warning against using out-of-date medicine as research suggests people are not throwing them away. According to a survey of 2000 people by One Poll, one in three consumers keep medicine past its expiry date because they think it could still be useful but it can be dangerous to use medication past its use-by date.

The research also shows more than four in 10 do not check the expiration date on items bought from the pharmacy, either over the counter or on prescription as most people assume that if it's still in the packet, it's safe to use.

Most drugs can be used for two to three years and NHS pharmacists stress it really is important to stick to them.

Community pharmacist Sultan Dajani said that taking expired medication is akin to playing "Russian roulette" with your health. He said: "Just as food can go off, medicines also deteriorate. Instead of healing, they can harm. For example, out-of-date paracetamol could affect your liver quite badly, causing nausea or vomiting."

Even if expired medications don't harm you, they can become less effective over time as the active ingredients become less potent - and tablets may not dissolve as well, they may not break down in the right places in your body, or get absorbed properly. Heat and moisture can also make pills go soft, swell up or decompose, changing how the ingredients work inside you. Sultan said: "After the expiration date, old medicines will either do nothing at all or in the worst-case scenario, make you ill."

The NHS says cough-and-cold medicines should only be kept for six months after opening as their contents tend to evaporate and separate.

Eye drops expire two years after they were made, and only last 28 days after opening. Regarding antibiotics, a study in BMJ Open revealed that one in 15 of us keep leftovers, and a third of those people hold onto them to use again the next time they get ill, even though you should finish the course when they are prescribed.