Adverse reactions: Talking to patients

Last updated: Thursday, November 18, 2021

There are several situations in which you will talk to patients about ADRs. For example, one common scenario is where someone is already suffering from a side effect; another is when you warn or advise a patient about an ADR that they might experience in the future.

Patients need to be aware of the nature of the ADR (the consequences), how likely they are to be affected, and how to manage it.


You should describe ADRs in a way that patients understand: most people have heard of the phrase 'side effect', for example, and know what it means but not 'adverse reaction' so don't use that. Avoid jargon, try to use everyday language, and check that patients comprehend what you are saying. You can prompt people with phrases such as "Have I explained that clearly?", or "Would you like me to go over that again?" It's helpful to tell patients that there will be a patient information leaflet that comes with each medicine. There are also websites for patients such as the NHS site.

Quick clinical question 
How would you describe the terms pruritus, oedema, paraesthesia, and insomnia to a patient?    Consider, then click for answer.
You could describe them as follows: pruritus = itchy skin;  oedema = build up of fluid that might make your ankles puffy;  paraesthesia = pins and needles;  insomnia = not being able to sleep.


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It is often beneficial to talk about the likelihood that an ADR will occur at an early stage. This helps a patient to put their risk into perspective. The EU has a classification system for the frequency of ADRs which is used in SmPCs and patient information leaflets. It uses two methods to express frequency – words and incidence figures:

  • Very common ≥ 1 in 10 (e.g. gastrointestinal disorders with metformin). 
  • Common < 1 in 10 but ≥ 1 in 100 (e.g. epistaxis with dabigatran). 
  • Uncommon < 1 in 100 but ≥ 1 in 1000 (e.g. pathological gambling with pramipexole). 
  • Rare < 1 in 1000 but ≥ 1 in 10,000 (e.g. rhabdomyolysis with simvastatin). 
  • Very rare < 1 in 10,000 (e.g. Stevens-Johnson syndrome with ciprofloxacin).

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. You might say something like "If we gave this medicine to one thousand patients, we reckon that only one person would get the side effect". Be careful with using percentages instead, as they are often misunderstood too.


You should advise patients if they need to self-monitor for any side effects, and if there are circumstances where an ADR warrants them seeking medical attention (e.g. haemorrhage when on anticoagulants). You can also advise if there are techniques to reduce the impact of an ADR (e.g. taking paracetamol for a drug-induced headache; taking a medicine after food to reduce gastrointestinal upset).

Besides offering your professional advice, you need to listen to the patient's own concerns:

  • "I don't always take those water tablets. They make me want to wee when I'm out shopping, and I can never find a loo."
  • "I'd rather put up with the pain than take morphine. It makes me so sleepy that I'm 'out of it', and can't enjoy time with my family."
  • "Can I be honest? That antidepressant didn't work and it just made me feel awful. I took it for two weeks and then gave up on it."

How would you respond to each of these situations?