LASA medicines: when two different drugs look or sound the same
LASA stands for look-alike, sound-alike — pairs of medicines whose names or packaging are close enough that one gets picked instead of the other. The MHRA has published pairs where this caused real harm, including deaths. This page covers the named pairs, tall man lettering, where in the dispensary the mistake actually happens, and what stops it. Two free resources to download and print.
Why this keeps happening
Almost every LASA pair shares its opening letters. Propranolol and prednisolone agree on the first four. On a busy bench, the eye reads the beginning of a word, recognises a shape, and fills in the rest. That is normal reading, not carelessness — which is exactly why willpower is not the fix. The fix is a system that does not rely on you reading perfectly every time.
The two medicines are then usually nothing alike. A beta blocker and a corticosteroid. An antipsychotic and a Parkinson’s drug. A drug for cystinosis in a nine-month-old and a leukaemia chemotherapy agent — a confusion the MHRA reported, where the child was admitted a month later with pancytopenia.
The pairs the MHRA has named
These come from Drug Safety Update, January 2018 and April 2013. Every one is a pair where a patient was reported to have received the wrong medicine. They are not the only risky pairs in your dispensary — they are the ones the regulator has published.
Notice the last one. Same molecule, same spelling for the first fourteen letters, completely different duration of action. Reading the first word is not enough.
Tall man lettering
Tall man lettering capitalises the part of the name that differs, so the difference is where your eye is already looking. It is used widely in UK hospital pharmacy, and there is nothing stopping you writing your own shelf labels this way.
It is not a cure on its own. It works because it is one more thing that has to line up before the wrong box leaves the shelf.
Where a LASA error actually happens
The name confusion is only the trigger. The error needs a gap somewhere in the journey from order to handout. NHS Specialist Pharmacy Service guidance sets out where those gaps sit.
A worked example: “the little white tablet for my blood pressure”
A regular patient collects a repeat. The bag has atenolol 50mg. She says she takes “the one for blood pressure, the little white one” — which fits both atenolol and amlodipine, and thousands of other tablets besides.
What catches it
You name the medicine rather than the colour: “This is atenolol, 50 milligrams — a beta blocker. Is that the one you have been taking?” She says her tablets are amlodipine and have been for two years. You stop, and you check the prescription against her record with the pharmacist before anything is handed over.
Nothing clever happened. You said the name and the strength out loud, and gave the patient the information she needed to correct you. She is the last safety check in the system and the most underused one.
Common mistakes
Relying on the shape of the box
Manufacturers change packaging and generics change supplier. The box you recognise this month may be a different medicine next month.
Treating “I have done this a thousand times” as a safety feature
Experience speeds up recognition, which is precisely the mechanism that goes wrong. Experienced staff make LASA errors too, and are less likely to be double-checked.
Not logging the near miss
The error caught at the accuracy check is the most useful data you have — it tells you where the next one will come from. Unlogged, it teaches nobody, and the shelf layout that caused it stays exactly as it is.
Free LASA resources
Both of these are free, need no sign-up, and are yours to print and use in your own pharmacy.
LASA quick reference
For the bench or the back of the dispensary door
Every MHRA-published pair with what each medicine is actually for, tall man lettering worked through, the five habits that stop an error, and what to do after a near miss.
LASA dispensary shelf check
For a team walk-round, about 30 minutes
Sixteen checks across storage and separation, selection and checking, environment and pressure, and learning from near misses — then space to write the three things you are changing as a result.
Doing the walk-round with a colleague beats doing it alone. You will disagree about which pairs are risky, and that disagreement is the finding.
LASA FAQ
What does LASA stand for?
Look-alike, sound-alike. It describes pairs of medicines that can be confused because their names look similar written down, sound similar spoken aloud, or come in packaging that is hard to tell apart. Some pairs are all three.
Is there an official UK list of LASA medicines?
There is no single definitive UK list. The MHRA has published pairs in Drug Safety Update where reported harm has occurred, and those are the ones on this page. Beyond that, the risky pairs depend on what you stock and how it is arranged, which is why the walk-round matters more than any national list.
What is tall man lettering?
Writing the differing part of a drug name in capitals — cloBAZam against cloNAZepam — so the difference sits where the eye is looking. It is widely used in UK hospital pharmacy and you can apply it to your own shelf labels.
Who should I tell about a LASA near miss?
Log it in your own near-miss record and tell the responsible pharmacist, however minor it seems. Concerns about look-alike or sound-alike names and packaging go to the MHRA at patient.information@mhra.gov.uk. Where harm has occurred from a medication error, report it on a Yellow Card.
Is LASA awareness part of pharmacy qualifications?
Yes. Safe selection, accuracy checking and error reporting run through both the Open Awards Level 2 Certificate and the Level 3 Diploma, and are assessed in your own workplace rather than by exam.
Explore PPets
If LASA is your starting point, here’s where PPets can take you next. Alongside our Level 2 Certificate and Level 3 Diploma, these are the apps and free support that go with them. Every learner uses one PPets login, so progress carries across every course and app.
Pharmacy Counter app
Practise naming the medicine out loud with AI customers. 64 scenarios across coughs, colds, hay fever, skin, pain and more. Every conversation scored on completeness and red-flag recognition.
Try free (3 scenarios)Get Into Pharmacy course
The starter course for anyone new to pharmacy. 10 modules covering roles, medicines, communication, safeguarding and Pharmacy First. Includes a QR-verifiable certificate.
Enrol now →POM Counselling Trainer
The natural next step from OTC. Counsel real-sounding patients on inhalers, anticoagulants, cytotoxics, steroids and mental-health medicines. BNF and EMC-aligned scoring.
Try free (inhalers)PPets Connect
Free 30-minute Microsoft Teams call with Daniel Dicker, our founder and a UK-registered pharmacy technician. For anyone getting into pharmacy or planning their next move.
Book a free sessionNot sure where to start? Book a free chat with Daniel and we’ll work out the right route for you.
Practise the conversation with AI patients
Free to try. No card needed. 3 respiratory scenarios on the free tier, or the full 64-scenario library on Individual and Organisation plans.
Start free →Turn what you do in the dispensary into a recognised qualification
Safe selection is the everyday skill. These are the regulated qualifications that put it on paper — externally verified by Open Awards, assessed in your own pharmacy by an assessor who visits in person, and with no exams. Next intake September 2026.
✓ Optional medicines counter assistant unit (+£200)
✓ One-hour live class once a week See the Level 2 course → Level 3 Diploma Pharmacy technicians · Open Awards 610/4031/9 £3,500 £4,200 Introductory price ✓ The route to GPhC registration
✓ Flexible one-to-one support, arranged around your working hours
✓ One-hour live class once a week See the Level 3 course →
No VAT to add. First payment starts your fee, balance by instalments with no interest or charges. Paying for it yourself? · What it costs · Apply now
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