¿Cuál es la diferencia entre un efecto secundario y una alergia a los medicamentos?

Last year in England, more than 1 billion prescriptions were issued. That's an awful lot of medicines, and an awful lot of potential for side effects as well as allergies.

#MedSafetyWeek is an annual campaign organised by the Medicines and Healthcare products Agency (MHRA). This encourages you to report any suspected side effects from medicines, a medical device incident, or if you believe a product isn't working as intended. The MHRA Yellow Card Scheme helps to detect and resolve potential safety issues with medicines and healthcare products.

#MedSafetyWeek 2024 (4-10 November)

How to tell if you have a drug allergy

A drug allergy is your immune system's reaction to a medicine. It's important to be aware of alimentarias, because if you take the same medicine again, the reaction could be worse.

Antibióticos - particularly penicilina - are a good example. The first allergic reaction many people have is an itchy rash. But once your body is primed to recognise something as an enemy, your sistema inmunológico reacts more strongly.

In worst case scenarios, it could result in a potentially life-threatening reaction called anafilaxia. This is a sudden itchy rash - like nettle rash - that's accompanied by wheezing, palpitaciones, mareos, swelling around the mouth, the lips and the tongue, and more.

Erupciones are usually due to allergy, and if you develop a rash shortly after starting a medicine it should always be checked out.

If you've ever been told you're allergic to any medicine, tell your doctor or pharmacist before they issue a new medicine.

How to tell if it's a side effect?

Side effects, rather than allergies, are far more common. Among the most common examples are:

With most medicines, side effects tend to be worse just after you start the tablets, and often settle within days or weeks at most. There are exceptions. With the blood pressure-lowering inhibidores de la ECA, dry seca - or even swelling around the face and lips (angioedema) - can develop more than one year after starting.

Read the leaflet

It's worth talking with your pharmacist and reading the patient leaflet for a full list of recognised side effects. However, it's important to remember that many side effects are very rare - they all have to be listed for legal reasons, even if most people don't get them.

Check the label of your medicine - some tablets may cause side effects if taken on an empty stomach, but will be fine with food.

Ask the pharmacist

I'm a huge fan of community pharmacists. This is yet another time they can be invaluable. Your community pharmacist really is the expert where medication is concerned.

They can tell you if a symptom is likely due to your medicine, whether it's likely to settle and what you should do. They can also advise on possible interactions between drugs you're taking. Do remember that herbal remedies and even food supplements can cause side effects or interact with prescribed medicines, so let your pharmacist know everything you're taking.

If you're having any symptoms you think might be related to your medicine, speak to your pharmacist first, unless it's a medical emergency. As with a GP appointment, it helps to be prepared. Make a list of any symptoms you have as well as any medicines you take - and that includes medicines bought over the counter. Even anti-inflammatory drugs like ibuprofeno, available without prescription, can cause tummy pain and bleeding.

Depending on what medicines you take, you may be able to book a review of your medicines with your pharmacist using Acceso del Paciente.

What about 'natural' remedies?

Many people assume that 'natural’ supplements or remedies are safe and don't have side effects. However, everything that has a positive effect can have a negative effect as well. The list is endless, but some examples include St John's wort, used for depresión, y aspirina - whether prescribed or taken for pain.

If you're taking the blood-thinner warfarina - commonly used if you have an abnormal heart rhythm called fibrilación auricular - you need to be particularly careful. It interacts with a host of prescribed medicines, supplements, and even food and drink - including alcohol, Brussels sprouts, and curly kale.

It's important to have regular blood tests when you're taking warfarin, but it's also a good idea to have a chat with your pharmacist about possible interactions, especially if your blood tests aren't stable.

With thanks to My Weekly magazine, where this article was originally published.