Allergy blood test

Overview

An allergy blood test is a simple test that measures the level of allergy-related antibodies in your blood. These antibodies are substances your immune system makes when you have an allergic reaction. The test can help identify which things you might be allergic to, such as pollen, dust mites, or certain foods.

Yes, allergy blood tests are a standard and common way to check for allergies. They are used worldwide.

Anyone who has allergy symptoms and needs to know what triggers them can have this test. It is safe for children, adults, and older people.

Symptoms

Common symptoms

• Sneezing and a runny or blocked nose
• Itchy, watery eyes
• Coughing, wheezing, or shortness of breath
• Skin rashes such as hives or eczema
• Stomach pain, diarrhoea, or vomiting (if food allergy)

Symptoms in children

• Frequent sneezing or stuffy nose
• Itchy eyes or ear infections
• Dark circles under the eyes (allergic shiners)
• Trouble sleeping due to coughing or congestion

Symptoms in older adults

• Allergy symptoms can be less obvious and may be mistaken for other conditions
• New or worsening shortness of breath or wheezing
• Itchy skin or rashes that are slow to heal

Causes

Main causes

• Allergies are caused by your immune system overreacting to harmless substances like pollen, dust mites, pet dander, mould, or certain foods.
• The body produces specific IgE antibodies against these triggers, which lead to allergic symptoms.

Risk factors

• Having a family history of allergies, asthma, or eczema
• Personal history of asthma or eczema
• Living in an environment with high levels of allergens
• Being exposed to certain allergens at a young age

When to see a doctor

See a doctor urgently if:

• If you have a severe allergic reaction, such as trouble breathing or swelling of the throat, call your local emergency number.
• If you have sudden symptoms after eating a food or getting stung by an insect.

Book a routine appointment if:

• If you have ongoing allergy symptoms that affect your daily life and over-the-counter treatments aren't helping.
• If you want to identify your allergy triggers to better manage them.

Diagnosis

Your doctor will talk with you about your symptoms and medical history. If they suspect allergies, they may recommend an allergy blood test. A small sample of blood is taken from your arm and sent to a lab. The lab measures the level of IgE antibodies to specific allergens.

Tests that may be done

• Specific IgE blood test (sometimes called a radioallergosorbent test or RAST)
• Sometimes a complete blood count (CBC) to check for signs of allergy

What to expect at your appointment

The blood test is similar to any routine blood draw. You may feel a quick pinch from the needle. There is no special preparation needed. Results usually arrive in a few days. Your doctor will explain what the numbers mean and how they relate to your symptoms.

Treatment

Treatment for allergies usually involves avoiding the things you are allergic to and managing symptoms with medicines or other therapies. Your doctor will work with you to create a plan that fits your life.

Self-care at home

• Avoid known allergy triggers as much as possible
• Keep your home clean and free of dust and mould
• Use air filters or keep windows closed during high pollen seasons
• Wear a mask when doing outdoor chores like gardening

Medical treatments

Doctors may recommend antihistamines, nasal corticosteroid sprays, or eye drops to control symptoms. For more severe allergies, they might suggest immunotherapy, which involves gradually exposing you to the allergen so your body becomes less sensitive. This can be given as injections or tablets under the tongue. Always follow your doctor’s advice on which treatment is right for you.

When is surgery considered?

Surgery is not a treatment for allergies. However, if allergies lead to problems like chronic sinusitis or nasal polyps, surgery may be considered for those complications. Discuss this with your specialist.

Living with this condition

Living with allergies means being aware of your triggers and taking steps to avoid them. Keep a diary of your symptoms to help identify patterns. Carry any prescribed emergency medicine, like an adrenaline auto-injector, if you have a history of severe reactions.

Lifestyle tips

• Monitor pollen and mould counts if you are allergic to outdoor allergens
• Use hypoallergenic bedding and wash sheets in hot water
• Keep pets out of the bedroom if you are allergic to pet dander
• Consider using a dehumidifier to control mould indoors

Diet and exercise

If you have food allergies, read food labels carefully and let restaurant staff know about your allergies. Exercise is generally fine, but if cold air triggers your asthma or allergy symptoms, wear a scarf over your mouth and nose when outdoors.

Mental health and emotional wellbeing

Allergies can be frustrating and can affect your sleep, mood, and social life. It is normal to feel stressed or anxious. Talking to a healthcare professional or joining a support group can help.

Prevention

Allergies themselves cannot always be prevented, but you can reduce your risk of developing new allergies by keeping your environment clean and managing existing allergies early. Some studies suggest that early exposure to certain foods may help prevent food allergies in children, but always talk to a doctor before making changes.

Vaccines

There is no vaccine to prevent allergies. However, allergy immunotherapy can help reduce sensitivity to certain allergens over time. This is not a vaccine but a treatment.

Screening programmes

Routine allergy screening is not recommended for everyone. It is usually only done when you have symptoms that suggest allergies and your doctor thinks it will help guide your care.

Complications

If left untreated

• Chronic sinus infections or nasal polyps
• Worsening of asthma symptoms, including asthma attacks
• Severe allergic reactions (anaphylaxis) that can be life-threatening
• Sleep problems and reduced quality of life

Long-term outlook

Although allergies can be lifelong, with the right management most people lead full and active lives. Identifying your triggers through a blood test is an important first step. Working closely with your healthcare team can help you control symptoms and prevent complications.

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