ASK THE DOCTOR: I've read that my heart pills may be dangerous 

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After having a pacemaker fitted, I was prescribed 20mg Xarelto (rivaroxaban). I have read it described as 'the most dangerous drug', and that thousands are suing the makers. I am 82 and healthy but terrified about adverse reports.

Rev John Theobald, Whitby, North Yorks.

The fact that lawyers are collecting cases of people who have suffered a side-effect from this drug is troubling to say the least.

'When making a decision about anticoagulation, it is essential to bear in mind dangers and complications'

I understand more than 3,000 lawsuits have been filed in the U.S. against the maker and distributor of Xarelto, alleging that the drug has caused unstoppable bleeding, even death.

However, to describe rivaroxaban as 'very dangerous' is unhelpful and emotive, and we must rely upon the evidence to make our decisions.

It's important to place the use of the drug in the context of the dangers of the condition being treated and consider the hazards of the alternative: warfarin. I hope that what I say may help you feel less concerned.

Rivaroxaban is a newly developed blood-thinner - a drug to prevent clotting - and is one of a group of three 'novel' anticoagulants; the other two are apixaban (brand name Eliquis) and dabigatran (Pradaxa).

These medicines are primarily used to prevent strokes in patients with atrial fibrillation, where the patient's heart beats irregularly, and often abnormally fast. There is a risk of a blood clot forming in one of the heart's chambers and travelling to the brain, causing a stroke.

The drugs are also used in patients with deep vein thrombosis, to prevent blood clots migrating from the deep veins in the legs up to the lungs causing a pulmonary embolism, which can be fatal.

'This drug is effective at preventing stroke. Although it is not without some risk, it compares favourably'

Prior to the arrival of these new anticoagulants, the only treatments available were heparin, which can be given only by injection, and warfarin, taken as a daily tablet.

It might seem more convenient, but warfarin is not without its problems as it's affected by what patients eat. This is partly because warfarin works by slowing the body's production of vitamin K, needed for the blood to clot. Food high in this (such as spinach and broccoli) can potentially interfere with the drug's effect.

As a result, patients can end up taking too much or too little. In the worst case scenario, unwanted and potentially dangerous clotting may still occur, or if the dose is too high, the risk is dangerous bleeding in the brain or elsewhere.

This is why patients taking warfarin must have regular blood tests to decide the dose.

Rivaroxaban and the two other new blood-thinners can be given in a standard dose without blood-testing (though an investigation by the BMJ in 2014 suggested blood-testing to adjust doses would make Pradaxa safer).

However, the disadvantage of these drugs is the lack of an antidote. If there is an adverse reaction - such as unwanted bleeding - the only solution is to wait a day or two for the drug to wear off.

In contrast, warfarin can, to a certain extent, be reversed by the injection of vitamin K.

But recent trial evidence suggests effective antidotes to the new drugs may have been identified.

The National Institute for Health and Care Excellence (NICE) has weighed up the pros and cons of warfarin and rivaroxaban. It now recommends rivaroxaban as an option, stating the drug should be used after an informed discussion about its risks and benefits compared with warfarin.

When considering its decision, the NICE committee heard evidence that in terms of the total number of significant bleeding events as a side-effect, there is no difference between the two drugs. There was a reduction in the number of fatal bleeds and intracranial haemorrhages (bleeding in the brain) - which can kill or cause permanent damage - with rivaroxaban, but a higher rate of bleeds in the intestine, which can be more easily treated before causing permanent damage.

When making a decision about anticoagulation, it is essential to bear in mind the dangers and complications of the condition being treated - in your case, I assume this is atrial fibrillation.

I hope that I can reassure you not to be terrified. This drug is effective at preventing stroke. Although it is not without some risk, it compares favourably with the alternative, warfarin.

I have had a bad case of constipation over the past few weeks. After a phone consultation with a GP, I was prescribed Laxido, which is good, but the struggle and straining has left me with a terrible aching in my back passage. It comes and goes but is very uncomfortable and sometimes makes my legs ache. The doctor didn't think it was anything to worry about.

Name and address withheld.

What concerns me is that you have not been examined and investigated further. You do not mention your age, but in older patients - by which I mean middle-aged and beyond - any alteration of bowel habit, such as constipation for several weeks, demands further investigation, even if prescribed laxatives seem to be helping.

I would not recommend taking the Laxido for longer than two weeks without seeing your doctor if your symptoms have not fully resolved.

You describe an ache that comes and goes and which, your longer letter explains, sometimes affects you at night. I can think of two possible explanations.

One is proctalgia fugax, a disorder in which there are fleeting but severe bouts of pain in the rectum with no other symptoms. It affects 5 to 10 per cent of people of almost all ages.

The episodes may last anything from seconds to minutes and typically occur a few times a year. Although there is some debate over the exact cause, it is thought to be down to an intense spasm of the rectum muscles.

To make the diagnosis, other causes of anal or rectal pain must be ruled out by examination. For example, haemorrhoids, abscesses, anal fissure, rectal cancer and inflammatory bowel disease may all give rise to this symptom.

A second possibility is chronic proctalgia, where bouts of pain last at least 20 minutes - again this is thought to be due to muscle spasms. To diagnose this, the patient must have had episodes for at least three months and all other causes must be excluded.

The best course of action is to see your usual doctor, discuss things further and perhaps be referred for an investigation.

This should include a flexible sigmoidoscopy - where a viewing scope is used to examine the rectum and a few inches of the colon - or a full colonoscopy (to examine the entire colon) to rule out any sinister cause of the change in bowel habit and the subsequent bouts of pain.

By the way... GPs must have 15 minutes with patients

'One of the greatest anxieties is having to see patients with such haste that there is a sense of cutting corners and compromising standards while short-changing people the simple humanity that's so important'

As I have so often said, the pressures on general practitioners have multiplied exponentially in the last few years - so much so that many senior doctors are opting for early retirement and young doctors are becoming reluctant to choose general practice as a career option.

When 20 to 40 patients visit a day, one of the greatest anxieties is having to see them with such haste that there is a sense of cutting corners and compromising standards while short-changing people the simple humanity that's so important.

Working day in, day out under such pressure can lead to mistakes. In the event of a complaint or an error that results in disciplinary procedures, the doctor is assumed guilty until proven innocent. Between 2005 and 2013, 28 doctors are thought to have died through suicide while undergoing investigation by the General Medical Council. Many had mental health problems that required support and treatment, but this went unrecognised by the powers-that-be.

However, here comes a breath of fresh air from the British Medical Association with the suggestion that GPs should spend 15 minutes with each patient - rather than the current ten - and that there should be a cap on the total number of consultations in each day.

The union has recognised that major changes are needed to limit the current strains crushing the professional life out of so many GPs. Such a move can only help, but it requires changes that are impossible to achieve - the first being a vast increase in the number of GPs.

It currently takes about 12 years to train a first-year undergraduate at medical school to become a fully-fledged general practitioner.

Topping up the numbers with doctors recruited from overseas may involve accepting far lower levels of training and even compromising standards - and that's assuming they can be lured here in sufficient numbers.

I am not sure there is a solution within the current healthcare model.

Has any politician the strength, courage and creativity to re-design the system?