Q&A: Danger of mixing drugs
There has been a warning about the risk of elderly people taking combinations of very common medications, some of which are available over the counter.
This has been linked to early death and declining brain function by researchers at the University of East Anglia.
The drugs are so widely used that around half of people over the age of 65 are thought to be taking them.
Many readers had questions and we have tried to answer some of them below.
What drugs are we talking about?
These are medicines for a wide range of conditions, a full list is available on the University of East Anglia website.
They include drugs for allergies such as the antihistamine chlorpheniramine, which is in Piriton.
Other drugs include the painkiller codeine, some antidepressants and warfarin which is used by patients with heart disease.
While the conditions they are used to treat vary widely, they all have one common side effect.
They are "anticholinergic" - which means they affect a key chemical in the brain which helps nerve cells communicate with each other.
How many is too many?
The study showed that the risk was cumulative - the more anticholinergic drugs a patient was taking, the greater the effect.
Each drug has an anticholinergic score: one for mild, two for moderate, three for severe. Total scores for a patient are calculated by adding together the scores for each drug they are taking.
Dr Chris Fox, who led the study, suggested that patients with a total score of four or more were at the greatest risk.
This could be as few as just two drugs.
What should patients do?
It is worth remembering that drugs are prescribed for a reason.
Nobody has suggested that patients should stop taking their medication. The consequence, for example, of heart patients who stopped taking the blood thinning drug warfarin would be dire.
The advice is for people "not to panic" and not to rush to their GP.
Researchers and doctors say that if people are concerned about their prescriptions they should discuss what medication they are taking as part of a regular appointment with their doctor.
How many people are affected?
One of the problems with the research is that the data is from 1991 to 1993 and it only looked at patients over 65.
Medicine has changed since then, including what drugs patients are given.
In the study, 48% of patients took at least one of these drugs and 4% were in the highest category (anticholinergic scores of four or more).
There are 12 million people over 65 in the UK. If the figures are the same now then nearly six million take these drugs, 480,000 are in the highest risk category.
My grandmother's sharp decline?
Richard from Swansea was concerned about his 90-year-old grandmother, asking: "She had a heart attack back in 2006 and was prescribed a myriad of different tablets from that day until now. I noticed a sharp decline in her mental capacity rapidly afterwards but always assumed it was due to her age. I would like to know if an investigation into her medicine could help her."
This is a question that can really be answered only by your family doctor who can look at what medicines your grandmother is taking. It is something you can ask at her next appointment.
What about younger people?
Andrew from Liverpool was among many people to ask: "What about patients under 65yrs who may be on these drugs long term?"
This study looked at people aged 65 or over. Other studies looking at younger patients are taking place, but have not reported yet.
There is one theory that the brain's protective shield - the blood brain barrier - is weaker in elderly patients, making them more susceptible to the effect of these drugs.
What safeguards are in place?
Doctors know that the more drugs a patient takes, the greater the risk of side effects.
GPs always balance the risk of prescribing a medicine with the benefits.
When a new drug is prescribed, GPs' computers automatically highlight all the side effects and how a new drug interacts with those already prescribed.
The Royal College of GPs said doctors "were very mindful of this" and that prescriptions were reviewed every 15 months.
The allergy drug is one of the most recognisable in this report. Chris, from Andover, asked why the "full list of drugs in the study and does not list Piriton".
Drugs often have multiple names such as one linked to their chemical formula and commercial brand names, which you would see on the shelves.
This list uses the chemical names, so in the case of Piriton that is listed as chlorpheniramine.