POM, P and GSL Medicines: What Is the Difference in the UK?

POM, P and GSL medicines are the three main UK legal supply categories for human medicines. POM means prescription-only medicine. P means pharmacy medicine: it can be bought without a prescription, but only from a pharmacy and in the presence of a pharmacist. GSL means general sale list, allowing supply through a wider range of retailers under the applicable conditions. The category concerns how a product is supplied, not a ranking of quality. [1]

These distinctions explain why one medicine can be picked up from a supermarket shelf while another requires a conversation at a pharmacy or a prescription. “Available without prescription” does not mean that all non-prescription products have identical rules.

Three categories in everyday language

Category	Ordinary route of supply	What to expect
POM	Supply against a valid prescription, subject to legal exceptions	Assessment by an authorised prescriber and appropriate dispensing
P	A pharmacy under pharmacist supervision	Questions about suitability and advice where needed
GSL	Pharmacies and other permitted retail settings	A presentation suitable for wider sale, with its own limits and warnings

The table describes the ordinary public-facing routes. Specific lawful services and exceptions can apply, but they are not permission for a retailer to ignore a product’s classification. [1]

Prescription-only medicines

POM products generally require a prescription from an authorised healthcare professional. The purpose is to place an appropriate level of professional control around conditions or medicines needing it. A prescription is not merely a payment document; it records a decision about the product to be supplied. [1]

Different healthcare professions may have prescribing rights within their scope. A person’s professional title alone does not establish authority to prescribe every medicine for every purpose. For a patient, the relevant question is whether the service provides an appropriate assessment and legitimate prescription route.

There are defined legal exceptions to routine prescription supply, including certain emergency and service arrangements. A pharmacist can explain whether one applies in a specific situation. The existence of an exception does not make the medicine generally available without prescription or justify self-directed online supply.

Pharmacy medicines

A P medicine does not normally require a prescription, but its supply is supervised through a pharmacy. Staff may ask who it is for, what symptoms are present, how long they have lasted and which other medicines are being used. These questions help identify whether the product fits the situation or whether another form of care is needed. [1]

A request can therefore end with advice or referral instead of a sale. That is part of the assessment, not evidence that the product has suddenly become prescription-only. Buying the same type of item previously does not guarantee that it remains suitable in changed circumstances.

For example, persistent symptoms, uncertainty about the intended user or possible ingredient duplication can make a brief conversation worthwhile. The product category creates a route to that check; it does not guarantee an automatic transaction.

General sale list medicines

GSL products can be supplied outside pharmacies, for example in supermarkets, where the relevant conditions are met. Their authorised presentations are considered suitable for wider sale. They still have instructions, contraindications and limits. [1]

The ability to choose a product from a shelf does not mean that it is suitable for every age group, every duration of symptoms or use alongside all other medicines. Read the label and leaflet, and seek advice if the problem persists or the instructions do not fit the intended user.

Convenience and clinical suitability are different questions. A nearby shop may make a product easy to obtain; that convenience cannot resolve whether an unexplained symptom needs professional assessment.

Why the same ingredient can appear in different categories

Classification can depend on the particular presentation, including strength, pack size, indication and intended users. One ingredient may therefore appear in more than one legal category. The classification of one pack must not be copied automatically to another. [1]

This is a common source of confusion when comparing prices online. A larger pack may not have the same supply category as a smaller one. A different formulation may have different rules. Compare the full product details before assuming that two listings offer the same type of access.

A larger milligram number also does not tell you the classification by itself. Strength is only one factor. The current product information is the appropriate reference for a particular medicine. [2]

What OTC means

OTC, or over the counter, is an informal term covering both P and GSL medicines. It is useful in ordinary conversation but is not a fourth UK statutory category. If a listing says only “OTC”, you may still need to establish whether pharmacist supervision is required. [1]

Do not treat another country’s OTC status as the UK answer. The same ingredient may be classified differently across jurisdictions or presentations. This guide is about UK human medicines, not Polish categories or veterinary supply classifications.

The UK and Northern Ireland context

POM, P and GSL are human-medicine supply classifications. They are distinct from the Category 1 and Category 2 framework used for regulatory rules under the Windsor Framework. “UK Only” is a packaging designation, not a fourth supply category or a statement that a prescription is unnecessary. [3][4]

Pharmacy oversight also has a territorial distinction: the General Pharmaceutical Council covers Great Britain, while the Pharmaceutical Society NI regulates pharmacies in Northern Ireland. Check the appropriate register when assessing a pharmacy service. [5][6][7][8]

An online checkout cannot determine the legal category. A website’s design, payment options or disclaimer should not be used to infer that a prescription requirement has disappeared.

Questions readers often ask

Does P mean that a pharmacist must prescribe it?

No. P describes supervised pharmacy supply without the ordinary requirement for a prescription. A pharmacist’s separate prescribing role is a different matter. [1]

Does GSL mean there are no risks?

No. It means the authorised presentation can be supplied more widely under the relevant conditions. Its warnings and instructions still apply.

Can a classification change?

Yes. The MHRA can reclassify medicines following assessment. Use current information for the exact product rather than assuming that an old purchase or article describes today’s status. [1]

Know the category and read the product

Use POM, P and GSL to understand the expected supply process, then read the exact product’s information. If the process offered by a seller seems inconsistent with the category, ask for clarification. A familiar ingredient name is not enough to settle the issue.

Editorial note: UK supply information verified on 9 September 2026. This article does not determine the classification or legality of an individual shop listing.