An allergy is when your body’s immune system is triggered by substances that are usually harmless, such as pollen, certain foods or insect stings. Your immune system will respond to an allergen like it would when attacking a virus, which can cause mild symptoms like itching or rashes or, in more severe cases, can lead to anaphylaxis, a life-threatening condition.

The first signs of anaphylaxis may look like usual allergy symptoms, such as a running nose or a skin rash. But within minutes, more serious signs will begin to appear. Anaphylaxis can come on suddenly and worsen very quickly1.

The main signs that someone is experiencing anaphylaxis include2:

  • Swelling of the throat or tongue
  • Difficulty breathing or breathing very fast
  • Difficulty swallowing
  • Wheezing, coughing or noisy breathing
  • Feeling tired or confused
  • Feeling faint, dizzy or fainting
  • Skin that is cold to the touch or skin, lips, or tongue that have turned blue, grey or pale (for people with darker complexions, this may be easier to identify on the palms of their hands or soles of their feet)

Some people may experience a second anaphylactic reaction – known as biphasic anaphylaxis – between 6-12 hours after the first reaction. That’s why it’s important to continue looking out for symptoms, even after administering an adrenaline pen3.

It’s easy to confuse allergies with urticaria (more commonly known as hives). Hives is a very common condition where a person’s skin breaks out in patches of red or white that may feel itchy. These rashes usually clear up on their own within 24 hours and rarely require medical attention. However, if hives are present and the person is also wheezing, experiencing severe diarrhoea, or vomiting, then anaphylaxis cannot be ruled out and urgent medical attention should be sought.

How do you know if you have an allergy?

If you suspect you, or your child has an allergy, contact your GP straight away for help identifying the cause. They will likely ask about the symptoms being experienced, how often they occur, and if you’ve noticed anything that seems to trigger them. Your GP may decide to refer you or your child to a specialist allergy service, particularly if your allergy seems severe or if it isn’t immediately obvious what is causing it.

Some people may decide to seek help for their allergies through private healthcare, rather than NHS services. If you do choose to go through a private healthcare provider but have already been referred to an NHS-operated allergy service, please let your GP know as soon as possible so that you can be removed from the waiting list. This will allow others to get the help they need sooner.

There are several ways healthcare professionals may diagnose your allergy, depending on the type of allergy you may have. The most common method is skin prick testing. This involves putting a small drop of liquid onto your forearm which contains a dose of the suspected allergen. They will then gently prick your skin and, if you’re allergic, an itchy, red bump should appear after a few minutes. The test is perfectly safe and isn’t usually painful, but you may find it a little uncomfortable.

If your GP suspects you have a specific allergy, they may run a blood test to confirm it or, if you have a suspected food allergy, they may suggest you do an oral food challenge. An oral food challenge is conducted in a controlled environment – such as a hospital – under the supervision of a trained specialist – you cannot carry out this test yourself at home. You will be given a very small amount of the allergen and a healthcare professional will closely monitor you for signs of an allergic reaction.

To learn more about allergies, visit Allergy UK