What does EXP mean on a medicine package?

EXP is short for expiry date. Next to it you may also see the words "Expiry date", "Use by", or "Best before". Most often only the month and year are given (for example EXP 06/2027), which means the medicine is good until the end of that month.

What is the difference between the batch number (LOT) and the expiry date?

LOT (the batch number) is an identifier for a production batch — a string of digits and letters used to trace the medicine, for example during a recall. It is not a date. You can spot the expiry date by the words "EXP", "Use by", or "Expiry date" and by the month/year format. The LOT tells you nothing about how long the medicine stays fit to use.

Where on a blister pack do I look for the expiry date and batch number?

On a blister pack (the foil strip with tablets), the expiry date and batch number are usually embossed or printed along the edge, near the seal — often in tiny print. You will find the same markings on the box and on the bottle label too; the leaflet, by contrast, gives you the storage rules and the after-opening shelf life. If you throw the box away, it is worth copying the expiry date down first, because it can be hard to read on the blister itself.

Is the medicine good until the date on the package, or until the end of the month?

If only the month and year are given (for example 06/2027), the medicine is good until the last day of that month — so until 30 June 2027. If a full day-by-day date is shown, that exact date applies. When in doubt, ask your pharmacist.

Where do I find the \"use within X after opening\" information?

The expiry date on the box applies to a sealed, unopened package. Once opened, some medicines — eye drops or syrups, for example — have a shorter shelf life. You will find this in the leaflet, in the storage section. The app does not work it out for you — it is information from each specific product's leaflet.

Why write down the date a medicine was opened?

Because it is not on the package — only you know when you opened the bottle of drops or the syrup. Noting the opening date (in a note next to the medicine, for example) lets you check later whether the after-opening shelf life from the leaflet has passed. Without that note, you are left guessing.

How does mojApteczka help keep track of expiry dates without copying them by hand?

When you add a medicine by photographing the package, the app reads the expiry date among other details and checks them against the Register of Medicinal Products, then uses colours to flag which medicines are nearing their date. You can add the opening date in a note next to the medicine. It is an organisational tool — it does not judge whether a medicine will still work.

EXPIRY DATE

EXP and LOT on Medicine Packaging: What They Mean

What do EXP and LOT mean on a medicine box? Learn how to read the expiry date, tell it apart from the batch number, and note the date you first opened it.

Tomasz Szuster 13 June 2026 7 min read

A medicine box and blister pack with the EXP, LOT, batch number fields and a spot for the opening date marked.

You are standing at the cabinet, a box in your hand that has been sitting here “for a while”. On the side, some small print: a few digits, some letters, then another string of characters. Which one is the expiry date? Is the longer number also a date, or something else? And is the medicine good until that date, or off-limits from then on?

It is one of those moments when the tiny letters on a package suddenly matter. The good news: there are only a few markings on a box, and once you know what they mean, you read them in a second. This guide shows you where to look, how not to mix up the expiry date with the batch number, and what is worth writing down yourself, because you will not find it on the package.

EXP — the expiry date

The most important marking is the expiry date. On packages you will find it under one of these labels:

EXP — short for expiry date,
Expiry date,
Use by or Best before.

They all mean the same thing: the date until which the manufacturer assures the unopened medicine keeps its declared quality.

Most often the date is written as a month and year, for example EXP 06/2027 or 06.2027. That means the medicine is good until the end of that month — in this example, until 30 June 2027. If a full day-by-day date appears on the package, that exact date is the one that applies.

The format varies depending on where a medicine was made: you may see 2027-06, 06/27, sometimes the month name spelled out in English. If the order of the digits is unclear, the safest move is to assume the cautious reading and — when in doubt — ask your pharmacist.

What to do with a medicine that is already past its date we covered separately in what to do with expired medicines — because tossing them in the bin or down the sink is not a good idea.

LOT and the batch number — this is not a date

Right next to the expiry date there is almost always a second string of characters — and it is the one that trips people up most. This is the batch number, marked with the word LOT, Batch no., or Batch. It looks something like LOT 4J21A or Batch 230815.

The batch number identifies a production batch. Every package made in the same batch carries the same LOT. What is it for?

Recalls. When a medicines authority suspends or recalls a medicine, it usually does so for a specific batch. That is exactly when the LOT number tells you whether your package is covered by the notice.
Complaints and reports. If something is wrong with a medicine, the pharmacist will ask for the batch number.

The key point: the LOT is not a date and says nothing about whether a medicine is still fit to use. Sometimes it contains digits that look like a year — but that is coincidence. You recognise the expiry date by the words “EXP” / “Use by” and the month/year format; the batch number by the word “LOT” / “Batch no.”. It is a simple rule that saves you mistakes.

Where these markings are — box, blister, bottle

The same details repeat in a few places, but they are not equally readable everywhere:

The box (carton) — usually on one of the sides or on the flap, in the largest and clearest print. This is the easiest place to copy from.
The blister (the foil strip with tablets) — the date and batch number are often embossed or printed near the seal, in tiny print, sometimes hard to read at an angle to the light.
A bottle, tube, or vial — on the label, or embossed on the base.

Hence a practical rule for keeping your cabinet in order: if you are getting rid of the box, first check whether the expiry date is legible on the blister itself. Very often it is not — and you are left with a strip of tablets and no idea how long they are good for. That is one of the main reasons homes end up full of medicines of “unknown age”. We showed this in our piece on how many expired medicines you have at home.

The opening date — what you will not find on the package

Here is something many people overlook: the expiry date on the box applies to a closed medicine, in its original packaging. Once opened, things can change.

Some medicines have a shorter shelf life after opening than the date on the box — because they lose sterility or stability. Classic examples are eye drops, syrups, some suspensions, and preparations you keep in the fridge. The “use within X after opening” information is not printed on the box — you find it in the leaflet, in the storage section. How to read a leaflet step by step we explain in our guide on how to read a medicine leaflet.

The catch is that even when you know that period from the leaflet, you still have to remember one thing nobody records for you: when you opened the package. The opening date is information only your home knows.

So it is worth building a simple habit: open a bottle of drops or a syrup — write down the opening date. It can be a pen mark on the label or a note in the app next to that medicine. Later you just compare it with the period from the leaflet, instead of guessing whether “this is still okay”.

How you store a medicine after opening matters too — we go into that in our piece on how to store medicines at home.

How to keep on top of this without copying everything by hand

Copying dates off every package is tedious and easy to get wrong — which is why, in practice, hardly anyone checks a home medicine cabinet regularly. This is where mojApteczka helps: instead of copying, you photograph the package.

Recognising a medicine from a photo reads the name, form, and expiry date among other details, and checks them against the Register of Medicinal Products kept by the national authority. You do not have to type in by hand what is already on the box.
Expiry alerts use colours to show which medicines are nearing their date or are already past it — green, orange, red. Checking expiry dates comes down to a glance, not pulling out every box.
The opening date, which is not on the package, you add in a note next to the medicine — where you will always find it, rather than on a scrap of paper that soon goes missing.
And when a second box of the same medicine turns up at home — often with a different batch number and a different date — duplicate detection by active ingredient flags it before you buy a third. That is especially handy when you are organising medicines for the whole family and packages reach the cabinet from different sources.

What the app does not do

To be honest: mojApteczka does not read the batch number (LOT) from a photo and does not work out the after-opening shelf life for you — because that information is in each product’s leaflet, not on the box. The app organises and reminds: it helps you gather expiry dates in one place and flags when they are coming up. It does not judge whether a medicine “will still work” after its date, and it does not replace a pharmacist or a doctor. It is a tool for running a home medicine cabinet, not for making medical decisions.

A quick cheat sheet to finish

EXP / Use by / Expiry date = the expiry date. Month and year only → good until the end of that month.
LOT / Batch no. = the batch number. For recalls and complaints. It is not a date.
On the blister, the details can be illegible — copy the date from the box before you throw it out.
The opening date is not on the package — write it down yourself; check the after-opening period in the leaflet.
A photo of the package in the app saves the copying, and the colour alerts make it easier to review expiry dates.

Reading a package is a small skill, but a medicine cabinet you can trust is built from small things like this — one where you know what you have, what is still good, and what you do not need to buy again.

Tomasz Szuster

Founder, mojApteczka

Frequently asked questions

What does EXP mean on a medicine package?: EXP is short for expiry date. Next to it you may also see the words "Expiry date", "Use by", or "Best before". Most often only the month and year are given (for example EXP 06/2027), which means the medicine is good until the end of that month.
What is the difference between the batch number (LOT) and the expiry date?: LOT (the batch number) is an identifier for a production batch — a string of digits and letters used to trace the medicine, for example during a recall. It is not a date. You can spot the expiry date by the words "EXP", "Use by", or "Expiry date" and by the month/year format. The LOT tells you nothing about how long the medicine stays fit to use.
Where on a blister pack do I look for the expiry date and batch number?: On a blister pack (the foil strip with tablets), the expiry date and batch number are usually embossed or printed along the edge, near the seal — often in tiny print. You will find the same markings on the box and on the bottle label too; the leaflet, by contrast, gives you the storage rules and the after-opening shelf life. If you throw the box away, it is worth copying the expiry date down first, because it can be hard to read on the blister itself.
Is the medicine good until the date on the package, or until the end of the month?: If only the month and year are given (for example 06/2027), the medicine is good until the last day of that month — so until 30 June 2027. If a full day-by-day date is shown, that exact date applies. When in doubt, ask your pharmacist.
Where do I find the \"use within X after opening\" information?: The expiry date on the box applies to a sealed, unopened package. Once opened, some medicines — eye drops or syrups, for example — have a shorter shelf life. You will find this in the leaflet, in the storage section. The app does not work it out for you — it is information from each specific product's leaflet.
Why write down the date a medicine was opened?: Because it is not on the package — only you know when you opened the bottle of drops or the syrup. Noting the opening date (in a note next to the medicine, for example) lets you check later whether the after-opening shelf life from the leaflet has passed. Without that note, you are left guessing.
How does mojApteczka help keep track of expiry dates without copying them by hand?: When you add a medicine by photographing the package, the app reads the expiry date among other details and checks them against the Register of Medicinal Products, then uses colours to flag which medicines are nearing their date. You can add the opening date in a note next to the medicine. It is an organisational tool — it does not judge whether a medicine will still work.