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Medicines information



As medicines are a crucial part of medical treatment, it is important to have a good understanding of them.

How can you get medicines?

Some medicines are available from pharmacists or supermarkets, while others require a prescription from your doctor or another healthcare professional.

The availability of medicines depends on the level of supervision experts believe is necessary before you use a particular medicine.

Under laws governing the supply of medicines, you can obtain medicine under three categories:

  • prescription-only medicines
  • pharmacy medicines
  • general sales list medicines

These are explained in more detail below.

Prescription-only medicines

Prescription-only medicines (POMs) need a prescription issued by a doctor or other suitably qualified healthcare professional.

You then take the prescription to a pharmacy or a dispensing doctor surgery to collect your medicine.

Pharmacy medicines

Pharmacy medicines (P) are available from a pharmacy without a prescription, but under the supervision of a pharmacist. You will need to ask staff at the pharmacy for this type of medicine because it is kept ‘behind the counter’ and is not available on the pharmacy shelves.

The pharmacist will check the medicine is appropriate for you and your health problem. They will ask you questions to ensure there is no reason why you should not use the medicine.

General sales list medicines

General sales list (GSL) medicines can be bought from pharmacies, supermarkets and other retail outlets without the supervision of a pharmacist. These are sometimes referred to as ‘over-the-counter’ (OTC) medicines.

OTC medicines include those that treat minor, self-limiting complaints, which people may feel are not serious enough to see their doctor or pharmacist about.

Can medicines change their status?

New medicines tend to be licensed in the POM category so that healthcare professionals can supervise their use during the first few years that they are available.

If a medicine proves safe in large numbers of patients over several years, the regulatory agency may consider changing its status from POM to P. If it continues to be safe for another few years, a switch to GSL status may be considered so it can be sold directly from retail outlets.

If a medicine switches from POM to P or from P to GSL, the active ingredient remains exactly the same. This means the medicine is just as effective as when it had to be prescribed by a qualified prescriber.

It also means there is the same risk of side effects if you take too high a dose or do not follow instructions on the label. Therefore, it is important you follow the instructions carefully.

How are medicines developed?

Before any medicine can be used to treat people, it has to be licensed. Licences are only granted if high standards of safety and quality are met throughout the development process and the product works for the purpose intended.

Potential medicines are first thoroughly researched using tissue culture, computer analysis techniques and animal testing.

If strict standards of safety and effectiveness are met, clinical trials involving humans can then be used. If a medicine passes all the phases of clinical trials, it can be licensed for wider use.

The whole process from discovery to licensing can take around 10-15 years.

Read more about licensing medicines.

How are medicines regulated?

No medicine is completely risk free, but attempts are made by the MHRA and EMA to ensure any medicine approved for widespread use is as safe as possible.

As well as a strictly monitored development process, medicines continue to be carefully regulated after they have been granted a license. This involves checking for problems, such as reports of previously unknown side effects.

In rare cases, medicines may be withdrawn if there are significant safety concerns or if the risks of the medicines outweigh potential benefits.

Read more about medicine safety and regulation.

Why do the same medicines sometimes have different names?

Many medicines have at least two different names – a brand name and a 'generic' name.

The brand name is usually what the medicine is called by the company that first discovered and developed it. The generic name is the name of the active ingredient in the medicine that makes it work.

Initially (for a few years), the company that developed the medicine is the only one that can sell it, which means they can choose the price. To make a profit from the very costly development process, this usually means the medicine is very expensive at this point.

Generic copies are allowed to be made once this period ends. Generic medicines are usually as effective as the brand-name medicine because they contain the same active ingredients.

Generic medicines are used more often for treatment, because they are as effective as the original medicine, but cost far less.

Read more about generic and brand-name medicines.

Medicine safety issues

While no medicine is completely risk-free, a licence indicates all the proper checks have been carried out and the benefits of a medicine are believed to outweigh the risks.

This licence is also known as a marketing authorisation.

Developing a medicine

Potential medicines are thoroughly researched using tissue culture, computer analysis techniques and animal testing.

All new medicines are required by law to be tested for safety, quality and effectiveness. Data is needed from two separate species of animal before a medicine can be used in clinical trials involving humans.

Clinical trials

Clinical trials are research studies carried out in human volunteers and patients that carefully test the safety and effectiveness of medicines, using strict criteria.

If clinical trials are going to be carried out in the UK, the manufacturer of the medicine must first apply to the MHRA for permission to test its medicine.

Read more about clinical trials and medical research.

Stages of research

Four stages of clinical trials are used to investigate a new medicine:

  • phase 1 – the medicine is tested in small numbers of healthy volunteers (up to 100 people) to find out how it works in the body and whether side effects increase at higher doses
  • phase 2 – the medicine is tested in moderate numbers of people (several hundred) with a particular condition or disease to see how effective it is, and to identify common, short-term side effects
  • phase 3 – information about the medicine is gathered from a larger number of people (often several thousand) to see how well it works and how safe it is
  • phase 4 – this happens after a licence has been granted and involves studies to monitor the medicine on an ongoing basis to see if there are any unexpected side effects or if the medicine causes problems in certain categories of people

Read more about the phases of clinical trials.

What information does a licence include?

The licence for a medicine includes information such as:

  • what health condition the medicine should be used to treat
  • what dose of the medicine should be used
  • what form the medicine takes – such as a tablet or liquid
  • who can use the medicine, for example, only people above a certain age
  • how long treatment with that medicine should last
  • warnings about known safety issues, such as side effects and interactions with other medicines
  • how the medicine should be stored
  • when the medicine expires

This information is usually included in the summary of product characteristics (SPC). This is a leaflet that comes with the medicine to inform healthcare professionals about how it should be used.

As well as a SPC, medicines should come with a patient information leaflet (PIL). This is a leaflet that gives the patient information about the medicine. However, a PIL is not necessary if all of the information fits on the label of the medicine.


The entire process of medicine development is controlled and monitoring continues after medicines become widely available.

In the UK, the Medicines and Healthcare products Regulatory Agency (MHRA) is the organisation that looks after the safety of prescribed medicines and other health devices and equipment. Its main job is to make sure that medicines and medical devices, from painkillers to pacemakers, work properly and are acceptably safe.

The MHRA works closely with the European regulator, the European Medicines Agency (EMA), which oversees the safety of medicines across Europe. In some cases, the EMA takes the lead in licensing medicines used in the UK.

Ensuring safety

No product is completely risk free, so the MHRA uses as much information as it can to ensure the benefits of medicines to patients justify any possible risks.

Both the MHRA and EMA routinely carry out inspections to check all parts of the medicine development process, from testing to manufacturing, are carried out in line with strict regulations.

The MHRA assesses the results of clinical trials to decide whether or not new medicines should be licensed for use. Clinical trials are research studies that carefully test the safety and effectiveness of medicines, using strict criteria.

No medicine or medical device can be used in the UK until the MHRA or EMA has given it a licence that sets out how it should be used and what health condition it should be used to treat. Read more about licensing medicines.

However, no medicine is completely risk free and medicines can affect different people in different ways. For example, depending on your age and sex and what other medicines you may be taking, a medicine might cause you to have a side effect that someone else who is taking the same medicine does not have.

Ultimately, you and your healthcare professional have to weigh up the pros and cons of each medicine when deciding on the most appropriate treatment.

Monitoring safety

The MHRA continues to monitor the safety of medicines once they are in wider use, by checking reports about any problems or defects and reviewing new scientific evidence on different medicines.

If any problems arise, the MHRA can take action to deal with it. This may mean alerting healthcare professionals about a potential issue with a medicine and withdrawing a medicine from the market if it becomes apparent that side effects outweigh the benefits.

Medicine brand names and generics

The names of medicines can often be confusing, as the same medicine can sometimes be called different things.

Many medicines have two names:

  • the brand name given to a medicine by the pharmaceutical company it is developed by
  • the scientific or generic name for the active ingredient of the medicine that is decided by an expert committee

For example, sildenafil is the generic name of a medicine used to treat erectile dysfunction. However, the company that makes sildenafil, Pfizer, sells it under the brand name Viagra.

Both medicines have the same clinical effect, but each separate manufacturer can give it a different name.

It is similar to buying branded goods or a supermarket’s own label; both products do the same job but the supermarket’s own version is usually cheaper.

Brand names

During the first few years a new medicine becomes available, it is usually marketed as a brand, under a name given by the pharmaceutical company that developed it.

Companies take out patents (exclusive rights) on each new drug they discover to ensure they regain the money they spend on its development – which can be as much as £1 billion – and make a profit.

Having a patent means only that company can produce the medicine for a certain length of time. In the UK, the standard patent lasts 20 years, although this can sometimes be extended by up to another five years.

On average, it takes the first 10-15 years of this period to develop the medicine and obtain a licence (read more aboutlicensing medicines). The company has the remaining years during which only they can produce and sell the medicine to recover their costs and make a profit. They give the medicine a brand name for marketing purposes to make it more memorable, such as Viagra.

Generic names

Once the patent protection expires, other companies can produce their own version of the medicine. For example, ibuprofen is the generic name of a medicine commonly used to treat pain and inflammation. There are many branded versions of ibuprofen, such as Nurofen and Hedex. However, it is also sold under the generic name ‘ibuprofen’ but made by different manufacturers, such as Boots or Tesco.

Generic medicines are usually cheaper because there are fewer research and development costs, but they contain the same active ingredient as the branded products.

Generic medicines go through the same detailed safety and quality requirements as the original branded product. Read more about regulating the safety of medicines.

Prescribing generic medicines

Prescribers (people who prescribe medicines, such as doctors) are encouraged to prescribe medicines by their generic name. This is because generic medicines are usually as effective as the branded versions, but can cost up to 80% less. It also gives the pharmacist the widest choice of products to dispense. This can be important, particularly if there is a shortage of a particular product.

Generic medicines with different activity

In rare cases, it is important for a patient to stay on the branded medicine previously prescribed for them, rather than changing to a generic medicine. In such cases, the branded medicine is the most suitable product.

Some examples of when you should keep taking your brand of prescribed medicine include:

  • Epilepsy medicines – these should be treated with care because different versions may have slight differences in the way they are absorbed, which can cause big differences in their effect; for example, prescribers may decide that the branded version of lamotrigine (Lamictal) is more suitable than the generic version.
  • Modified-release preparations of medicines – such as modified release versions of theophylline, nifedipine, diltiazem and verapamil; a branded version may sometimes be a better option than the generic equivalent as they can be absorbed differently.
  • Ciclosporin – a medicine that suppresses the immune system (the body’s natural defence system); different branded versions may cause different levels of ciclosporin in your blood.
  • Mesalazine – which is used to treat ulcerative colitis (a long-term condition that affects the colon); the way that mesalazine is absorbed varies between different brands.
  • Lithium – this treats a number of mental health conditions; different brands vary widely in terms of how much of the medicine is absorbed and becomes active.
  • Beclometasone dipropionate CFC-free inhalers to treat asthma – there are two inhalers that contain the same active substance (beclometasone dipropionate), but one is much stronger.
  • Any product where the generic name could cause confusion, such as hormone replacement therapy (HRT) and insulins (used to treat diabetes).
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Important: Our website provides useful information but is not a substitute for medical advice. You should always seek the advice of your doctor when making decisions about your health.

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