Shortages of medicines in the NHS are nothing new. Last month it was low-dose aspirin used to treat and prevent heart disease, stroke and other conditions. This month it’s high-dose co-codamol, one of the most commonly prescribed painkillers in the UK.

Manufacturing issues in India, the world’s largest producer of generic (non-branded) medicines, have meant that it’s becoming impossible for many people to collect their regular prescription, and the situation is unlikely to improve until June at the earliest. So, if you are one of the million or so people thought to be affected, what are your options?

Co-codamol is a mix of the opioid codeine and paracetamol, and it comes in three commonly used strengths. The weakest version (8mg of codeine and 500mg of paracetamol for each tablet or capsule) is available over the counter from pharmacies, while stronger versions containing more codeine (15/500 and 30/500) are prescription only. The standard dose for all of them is two tablets/capsules, every four to six hours as required, up to a maximum of eight tablets a day.

Codeine is a prodrug that requires conversion to morphine in the body and the impact depends on how people metabolise it. About 1 in 10 people are poor metabolisers and end up with lower levels of morphine and little pain relief.

At the other end of the spectrum, fast metabolisers end up with, dose for dose, much higher levels which, while giving faster and better pain relief, also lead to more side-effects (see below). If you have been prescribed high-dose co-codamol (30/500) and reacted badly, it could be that you are a fast metaboliser and are better sticking to weaker versions.

The shortage, which applies to the 30/500mg dose, has prompted lots of guidance on what to do about it from relevant bodies across the NHS, and while that varies, there are two common themes: first, advice on switching to alternatives, and second, using this as an opportunity to review whether some patients really benefit from regular continuing high dose co-codamol.

The role of opioids such as codeine in managing long-term pain, other than in people with cancer, remains controversial. Research suggests they don’t work that well, if at all, but that they cause lots of side-effects, ranging from constipation, nausea and itching, to fatigue, confusion, weight gain, sexual difficulties and dependence.

The lack of efficacy in long-term pain lasting more than three months seems counterintuitive to most people — and often to their doctors — so when the tablets aren’t helping, patients end up being prescribed ever higher doses even though it’s often just flogging a dead horse.

It’s a complex issue that I have covered before. Suffice to say that if your 30/500 co-codamol is working well for you and you don’t have troublesome side-effects, you will need to talk to your prescriber about alternatives (see below).

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However, if they have never really helped or you do have side-effects, now might be a good time to consider switching to a weaker version and exploring other options to help manage your pain. Approaches will vary from individual to individual but don’t be surprised — or offended — if your doctor suggests using the present shortage as an opportunity to taper your dose down.

Assuming they are working well for you, what happens when your supply runs out, as it already has in my area? The most common option is to switch to separate paracetamol and codeine tablets, or drop down to the 15/500 preparation and take it more frequently (still no more than 8 a day). Both are still available but supplies are fast dwindling as people swap.

Another option is to switch to stronger opioids such as tramadol or morphine, or to the NSAID anti-inflammatory family like naproxen. Guidance generally advises against both because of the risk of side-effects (particularly bleeding from the gut with NSAIDs) and, if such a move is indicated, advises that it should only be done on an individual basis after careful consideration.

And herein lies another problem: the effect on already stretched GP surgeries and pharmacies. There are an estimated 50,000 people taking 30/500 co-codamol in the Lancashire and South Cumbria region alone, where the drug accounts for 1 in 3 of all opioid painkiller prescriptions. That is a lot of potentially angry and upset patients struggling to get hold of their GP. June is a long way off for all of us, but will feel even further for those having to deal with daily pain.

If it was me, I would try to manage on 15/500, at least in the short term. But I am very aware it’s not me.

For more advice and useful links see nhsgrampian.org

The facts about codeine

• Codeine is a weak opioid with the maximum daily dose (240mg) being the equivalent of about 24mg of morphine.
• To provide effective relief, codeine has to be converted in the body to morphine and poor metabolisers (5-10 per cent of the population) will derive little or no pain relief but can still get side-effects like sedation, dizziness, dry mouth and blurred vision.
• Very fast metabolisers (1-2 per cent of the population) risk more serious morphine related side- effects, including opioid poisoning respiratory depression (slowed breathing). This is particularly dangerous in children and codeine is contraindicated in the under-12s.
• Most people lie between these two extremes (intermediate metabolisers).
• Without genetic testing, there is no way to tell which group you are in, other than experience from previous dosing. Although a family history of close relatives who have had reactions to codeine — or had no pain relief from it — can be a clue.