1. Prescribing a drug to someone with a known allergy

In the MDU's experience this is the most prevalent type of prescribing error, with penicillin the most common drug being wrongly administered.

Patients cannot always give a reliable history in relation to drug allergies, so it's important to check their records for reported allergies and to see what drugs have been prescribed in the past.

Your trust or practice should have appropriate systems in place so that any flagged allergies can be easily seen by any doctors accessing a patient's records.

Make a note in the patient's records that you have asked them about their allergies, in case you need to defend your prescribing decision later.

2. Prescribing the wrong drug

In the past, wrong drugs were sometimes dispensed by pharmacists when they had difficulty deciphering a doctor's handwriting. But computer-generated prescriptions can pose their own set of risks, when a doctor selects the wrong drug from the drop-down menu on the electronic system.

Some examples include choosing penicillamine instead of penicillin, or choosing the wrong route of administration – such as ear drops instead of eye drops.

When selecting a medication from a drop-down menu, take the time to make sure you're selecting the right one. It may sound straightforward, but it's a relatively easy oversight to make when you’re in a rush or at the end of a long and stressful day.

3. Prescribing the wrong dose

This can also easily happen when choosing from a drop-down menu, where a drug is listed with different preparations and strengths, or a GP may simply choose the wrong dose for that particular patient in those circumstances.

There is a particular risk when prescribing for children or the elderly, who may require smaller doses, or where the dose needs to be calculated based on body weight.

The MDU has seen several claims against doctors involving opiates, where a higher than intended strength was prescribed, resulting in an overdose. Another common error was prescribing a drug at the wrong frequency, such as methotrexate daily instead of weekly.

4. Failing to consider drug interactions, side effects and contraindications

Problems can arise when doctors prescribe a medication without paying attention to any possible interactions with other drugs the patient is taking. This can lead to unpleasant side effects for the patient, or the situation can change and the drug is no longer appropriate – for example, when a patient on a long-term anti-epileptic therapy becomes pregnant.

Ask the patient if they are currently taking any other medication, and check their clinical record for other drugs they may be prescribed. Make a note of your investigation in the patient's records.

5. Failing to monitor appropriately

Some drugs, such as phenytoin, require monitoring because they have a narrow therapeutic range. Some drugs require patients to be monitored to look for side effects, for example checking renal functions in patients taking ACE inhibitors.

Your trust or practice should have suitable arrangements in place for monitoring, follow-up and review of patients' prescriptions, taking into account their needs and any risks arising from the medicines. However, it is the prescribing doctor's responsibility to make sure this takes place, and this includes repeat prescriptions for medication that has been initiated by a colleague.