Understanding medicines

Medicines can be confusing. They can cure an illness or improve our symptoms, but they can also be dangerous if taken incorrectly. This leaflet aims to explain a little more about medicines, how to understand your prescription and who to ask for more information.

Pharmaceutical companies – companies who make medicines – are always carrying out research to find new medicines or to discover new ways of using existing medicines.

It is never a quick process to develop a new medicine. The ones that make the news have usually been in development for tens of years costing millions of pounds before they are released.

Once a pharmaceutical company has come up with a new medicine, it goes through several clinical stages of testing to make sure it works as designed and to discover any possible side effects. These tests are called clinical trials and can last for many years.

Once the clinical trials have been completed, the data and outcomes are submitted to the Medicines and Healthcare products Regulatory Agency (MHRA). The MHRA then review the medicines safety and effectiveness. The MHRA then decide whether or not to give a “license” for the medicine, so it can be used in the UK, for a specific disease or condition.

The MRHA monitors the medicines and products license continually and can withdraw the license if concerns are raised. For instance, the Yellow Card scheme is the way to report side effects, particularly if they are not mentioned in the Patient Information Leaflet (PIL) or are severe.

You can read more about the Yellow Card scheme.

Anyone can report side effects or problems with medicines or products to the MHRA. It is not limited to doctors and pharmacists.

There are two main categories of medicines available in the UK:

• prescription-only medicines (POMs)
• over-the-counter (OTC) medicines.

POMs are medicines which can only be given with a prescription – you can’t just buy them off the shelf. A prescriber – like a doctor or a pharmacist – needs to have issued you with a prescription to confirm that you need them. POMs tend to be medicines that need closer supervision or regular monitoring by a health care professional.

It’s worth noting that doctors often prescribe POMs for which there is an OTC alternative. If you pay prescription charges, it is often worth asking the pharmacist if there is an OTC alternative.

OTC medicines are those that you can buy without a prescription, such as mild painkillers, cough and cold remedies and antacids. You can buy some of these from a regular shop, but others can only be bought from a pharmacy.

Even though you can buy OTC medicines without a prescription, you should still take care. Taking them in the wrong way or combining them with other medicines can be dangerous.

Find out more information about OTC medicines.

Your prescription is a request from your doctor to a pharmacist saying that you need a particular medicine. It’s a bit like a permission letter to say you can have the medication. You might also hear it called a ‘script’. These days, most prescriptions are electronic, but you still might get one that is handwritten.

At GOSH, we can’t send a prescription straight to your community pharmacy from our electronic system, it has to be dispensed directly from our pharmacy. If we do not have the medicine in stock, or you prefer to collect it from your local pharmacy, we can give you a GP note to ask for a prescription to be written by your GP. This can then be dispensed by your local pharmacist. Bear in mind, some medicines we supply are specialist, so your GP might not prescribe it. In this case, you will get your repeat prescriptions from GOSH. If you are not sure, ask your doctor or pharmacist about how to get more medicine.

In the community pharmacy, when you hand over your prescription, you should complete the back of the form if you are collecting the medicine on behalf of someone else or you are receiving certain benefits.

If the medicine can interact with other medicines, the pharmacist may ask you some questions. They will then dispense and check the medicine is correct against the prescription. A label is added to the medicine/s with your details and instructions on how to take it.

Your prescription should contain your name and address (and age if under 16 years old) and details of the medicine(s). The name and strength of the medicine is usually given first, followed by the dosage and frequency.

When you receive the medicine, check that you understand the label. It will also state any special instructions, for instance, whether it should be taken with or after food or on an empty stomach. The pharmacist will check that you understand the instructions before you leave the pharmacy.

If you live in England, you’re entitled to free NHS prescriptions if you’re:

• Aged 16 and under.
• Aged between 16 to 18 and in full-time education.
• Receiving certain benefits.

If you have a specific long term medical condition, you may also be able to get a Medical Exemption Certificate (MedEx) which entitles you to free prescriptions.

If you pay for your prescriptions and are likely to need a number of prescriptions across the year, it’s worth checking if an NHS Prescription Prepayment Certificate (PPC) could save you money.

If you live outside of England, the situation may be different so check with your pharmacist.

All licensed medicines now come with a PIL. This is the bit of paper inside the medication box which is usually quite long and wordy!

PILs are provided by the manufacturer and describe the medicine, how it works, and how it should be taken. The PIL will also contain possible side effects. This can be worrying but remember that some of the reported side effects are extremely rare.

If you are concerned about the information in the PIL, please talk it over with your pharmacist.

Some medicines were originally developed to treat one condition but were found to help a completely different condition. This means a PIL might not mention your condition, might seem misleading or it might even say that the medicine is not recommended for children and young people. This is called ‘off-label’, ‘off-license’ or ‘unlicensed’ use.

This can mean different things:

• It might be that the medicine has a license for a certain condition, but not the condition it has been prescribed for.
• It might also mean that the medicine has a license for the condition it has been prescribed for, but not for the age of your child. This situation is relatively common for medicine use in children. Manufacturers may not have included children in the clinical trials used to test the medicine so cannot include them in the licence application.
• It might be that the medicine has a license in a different country, but not in the UK.
• In other circumstances, medicines may not have a license at all, often because they are used to treat very rare conditions.

However, you can be assured that your doctor has only prescribed an ‘unlicensed’ medicine because they think that the medicine will benefit you and no licensed alternative is available.

More information about unlicensed medicines for children, Medicines for Children

Recently, some changes have come about to increase the number of medicines being developed and tested specifically for children. This means that fewer ‘unlicensed’ medicines will need to be used, in the long term.

You can ask your medical team about your medicines. Pharmacists are ‘medicines experts’ and can help with any questions or concern you may have.

Most community pharmacies – located on the high street or in big supermarkets– have a quiet room where you can talk to a pharmacist in private. You can ask them about anything to do with your medicines including side effects, how to take it, and what medicines you shouldn’t take together. You don’t need an appointment to do this. Many also have a selection of health information leaflets as well.

If you’re a GOSH patient, you can also use the MyGOSH app to ask questions about your medicines or ask your pharmacist.

• Pharmacy medicines information: 020 7829 8608 (Monday to Friday from 9am to 5pm)
• GOSH switchboard: 020 7405 9200

Please note we can only give advice to patients and families currently being treated at GOSH.

We work hard to ensure that our information leaflets are accurate, complete and kept up to date. The information is based on evidence available at the time of publication. This leaflet is not intended to replace discussions with your medical team.

Written by: Medicines Information

Reference number: 1125MED0003

Last reviewed: November 2025

Next review due: November 2029