Allergies: the facts behind the rash
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Allergies: the facts behind the rash


Allergies are extremely common in the UK, with one if four people thought to be affected. Symptoms range from trivial annoyances to life-threatening reactions. If you’re worried about an allergy, our doctors are on the other end of the phone to talk you through it.

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Allergy Symptoms

If you have any of the following symptoms, you may be suffering from a life-threatening allergic reaction. You should use an Epipen and call 999 immediately:

What causes allergies?

There are many allergens out there that can cause symptoms, but here are some common culprits:

Hay fever

Hay fever is extremely common. It is caused by an allergy to pollen, and typically happens in the summer months. It is a type of allergic rhinitis.

Do I have a true allergy?

There is a subtle difference between being sensitive/intolerant to something and being allergic to it. Take latex as an example: many people will develop irritation between their fingers if they wear rubber washing-up gloves. This is because they are sensitive or intolerant to latex. However, if your hands swell and your lips tingle if you come into contact with latex, it means you have a true latex allergy and you should speak to a doctor about it. Also, be careful if you’re going into hospital for any tests or procedures, as latex gloves are often used by medical staff and they may not realise you’re allergic to it.

What happens to the body during an allergic reaction?

Allergic reactions occur when the immune system starts to be ‘hypersensitive’ to substances that normally wouldn’t cause problems. When immune cells come into contact with these substances (‘allergens’), they cause a chain reaction of events that ends with the release of a substance called histamine. Histamine causes blood vessels to dilate and become more permeable (leaky) to water, causing swelling, redness and warmth. When this process happens in the nasal lining, it causes a runny nose. Histamine also affects nerve endings, leading to itching or pain.

So why does the immune system keep reacting in this way time and time again? Well, your immune cells produce antibodies, which are protein structures that normally tell your body what to do when it is attacked by things like bacteria or viruses. In allergies, this process goes wrong, and your body thinks it is being attacked every time you come into contact with the substance you’re allergic to. The antibodies stay in your system and remind your immune cells to react in the same inappropriate way every time you’re exposed to your allergen, which is why the problem can last for years.

Children more commonly are affected by allergies than adults, and it is possible to grow out of them.

When should I contact a doctor?

If you’re experiencing breathing difficulties or a swelling in the throat, you must immediately use an Epipen and call 999. If you’ve been exposed to an allergen and you notice the swelling and redness getting worse and spreading, you should seek urgent medical attention, as it may spread to the throat.

If it’s not an emergency, but your allergy is causing you distress and inconvenience, speak to a doctor. There are prescription-only medications that can be very effective, and that our GPs here at Dr Morton’s can provide for you (see more in the ‘Treatment for allergies’ section below).

How are allergies diagnosed?

Often you don’t need any formal testing to be diagnosed with an allergy, as a doctor will normally be able to tell from your symptoms and your medical history.

However, if the cause of your allergy is not clear, you may be sent for further tests. Speak to your regular GP if you would like to be referred.

Skin prick testing

During a skin prick test, droplets of fluid are placed on your arm. The droplets each contain a substance that you might be allergic to. Then, the skin beneath the droplet is pricked gently with a needle, and a red, itchy bump will appear if you are allergic to that particular substance.

Patch tests

If you suffer from contact dermatitis, you may be referred for patch testing. It involves sticking metal discs to your skin that contain the suspected allergen, to see if you react to it.

Blood assays

This is a blood test. A sample of the blood is taken and tested in the lab for antibodies to various substances.

Elimination diet

This involves avoiding particular types of food to see if your symptoms get better. You may gradually be asked to re-introduce food types one at a time to see which ones cause a reaction.

Please remember that you should not attempt any allergy testing without the guidance of a qualified medical professional.

Treatment for allergies

If you suffer from hay fever and would like treatment, you can order one of our specialist prescription packs, containing non-drowsy anithistamines, from our hay fever page. One of our highly experienced, GMC registered doctors will check your order, and if they’re happy to prescribe it, your chosen pack can be delivered straight to your door.

The medications in this pack can also be very helpful in combatting other allergies, so please do get in touch with us if you’d like a custom prescription.

Treatment for severe allergies

For those who may be at risk of anaphylaxis, it is advisable to carry an EpiPen at all time. EpiPens contain adrenaline which quickly relieves the allergic reaction. It is important to note that if you ever need to use your EpiPen because you’re having a severe allergic reaction, you should ring 999 immediately.

If you’re with someone who is having a severe allergic reaction, get the suspected allergen away from them if possible and call 999. Lie the person flat on the floor with their legs raised and use an Epipen if one is available.

Some allergic responses, such as gluten allergies, may take years to come to light and can be difficult to treat. If you are concerned that you may be allergic to something, it is best to speak to a doctor.

This page was last updated on 30/03/2016

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