Anticholinergics: Talking to patients

Last updated: May 13, 2022

Describing the whole array of anticholinergic side effects to patients or carers is difficult. It may be better to explain the cause of existing reactions that you believe are a problem, or to advise about potential future side effects that would be of particular concern.

Nature of side effects

Try to use everyday language, and avoid jargon such as 'urinary retention'. It's helpful to talk about side effects in terms of what the patient may actually experience. So you may want to use phrases such as 'feeling sleepy during the day' and 'finding it hard to swallow' rather than sedation and dry mouth. Ask patients if they understand what you are saying and invite them to ask questions.

Manufacturers' patient information leaflets, available via the eMC, have comprehensive lists of potential side effects for many medicines. The NHS website has patient-friendly guides to many medicines that also include some side effects and how to manage them.

Likelihood

It can be beneficial to talk about the likelihood that a side effect will occur. This helps a patient to put their risk into perspective. There is a classification system for the frequency of side effects which is used in manufacturers' SPCs and patient information leaflets, both available on the eMC. It uses two methods to express frequency – words and incidence figures. For example:

• Very common ≥ 1 in 10 (e.g. tachycardia with amitriptyline). 
• Common < 1 in 10 but ≥ 1 in 100 (e.g. blurred vision with carbamazepine). 
• Uncommon < 1 in 100 but ≥ 1 in 1000 (e.g. sleepiness with solifenacin). 
• Rare < 1 in 1000 but ≥ 1 in 10,000 (e.g. tachycardia with tiotropium inhaler). 

You can access this information from the Undesirable Effects sections of a drug company product summary (called an 'SPC'). You will need to use your judgement to decide which method(s) of expressing frequency are going to be most appropriate or meaningful to the patient. However, a lot of people are not very familiar with phrases such as "1 in 1000" so you'll need to re-work this into a more patient-friendly description.

Managing side effects

You should advise patients if they need to self-monitor for any side effects, and if there are circumstances where they should seek medical attention (e.g. if you fall over). You can also discuss techniques to reduce the impact of a side effect (e.g. taking a laxative for drug-induced constipation), or suggest that the patient speaks to a pharmacist about managing it.

Finally, advise patients at risk to be careful about over the counter (OTC) medicines because a number of cough and cold, antihistamine, insomnia, or travel sickness medicines can have anticholinergic side effects. They should ask their pharmacist for advice before buying anything.