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Diamine Oxidase
99.00
This test measures Diamine Oxidase (DAO), the enzyme responsible for breaking down histamine. Low DAO levels are linked to histamine intolerance and unexplained symptoms.
Turnaround time
2 weeks
Biomarkers count
1
Same-Day Appointments
UKAS Accredited Labs
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Under 18? Patients under 18 can only be seen at GB Medlabs and Clinilabs, Monday to Friday only.
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Details about Diamine Oxidase
What is a Diamine Oxidase (DAO) test?
A Diamine Oxidase (DAO) test measures the level of DAO enzyme activity in your blood. DAO is produced mainly in the gut and is responsible for breaking down histamine from foods and the body.
When DAO levels are low, histamine is not properly cleared, leading to symptoms known as histamine intolerance, which can mimic allergies, migraines, gut disorders, and skin problems.
Why do I need a DAO test?
Histamine intolerance is frequently misdiagnosed because symptoms are varied and often unexplained.
Reasons for testing include:
• Frequent headaches or migraines
• Flushing or facial redness after food
• Unexplained rashes or itching
• Bloating and digestive discomfort
• Runny nose without infection
• Food reactions (cheese, wine, fermented foods)
• Chronic fatigue
• Brain fog
Symptoms that often prompt testing include:
• Palpitations after meals
• Anxiety after certain foods
• Diarrhoea or cramps
• Skin irritation
Benefits of the test
1. Identifies histamine intolerance
2. Assesses gut enzyme function
3. Helps explain food-related symptoms
4. Useful for migraine sufferers
5. Supports investigation of unexplained rashes
6. Links gut health and systemic symptoms
7. Guides dietary changes
8. Supports targeted supplementation
Expanded benefit explanation
Low DAO activity prevents proper histamine breakdown, causing widespread symptoms. Identifying this allows effective dietary and treatment strategies.
Step-by-step — How testing works
We offer two UK-wide testing options:
Clinic testing
• Choose nearest UK clinic
• Blood sample collected
• Laboratory analysis performed
• Results securely returned
Home visit (+£60)
• Phlebotomist visits you
• Blood sample collected safely
• Sample sent to lab
• Results delivered confidentially
Your results explained
Low levels
May indicate histamine intolerance and reduced gut DAO production.
Normal levels
Suggest histamine breakdown is functioning normally.
High levels
Rarely clinically significant.
How It Works
Simple steps to get your results
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Book Online
Choose your test online and book in seconds. Select your preferred clinic location or home visit option.
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Visit or Test at Home
Attend one of our UK or London clinics, arrange a home nurse visit, or use a finger-prick kit where available.
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Get Your Results
Your sample is analysed by accredited UK laboratories, with secure results delivered directly to you.
Take control of your health with London Blood Tests
WhatsApp UsHow to Prepare for Your Test
Follow these guidelines for accurate results
Sample Timing
Where possible, attend your blood test between 7am and 12pm. Please wait until any short-term illness or infection has fully resolved before testing. Avoid intense exercise for 24–48 hours beforehand, as this can affect certain markers.
Fasting & Hydration
Fasting is not always required, but some tests may recommend it. If fasting is advised, avoid food for 8–12 hours before your appointment and drink water only. Stay well hydrated, as this helps with sample collection and accuracy.
Medications & Supplements
Continue prescribed medications unless advised otherwise by your clinician. Avoid vitamin, mineral, or biotin supplements for at least 24–48 hours before your test, as these can interfere with results. If you are unsure about any medication or supplement, please let us know before your appointment.
Hormones & Menstrual Cycle
For hormone-related tests, timing within your menstrual cycle may be important. If relevant, follow any specific guidance provided on your test page.
If you have any questions or special circumstances, our team is happy to advise before your appointment.
Frequently Asked Questions
It measures the activity of diamine oxidase, the enzyme responsible for breaking down dietary histamine.
No. Histamine intolerance is non-allergic and does not involve IgE antibodies.
No fasting is required.
Yes. Antihistamines, antidepressants, painkillers, and alcohol may reduce DAO activity.
Yes. Treating gut inflammation, adjusting diet, and addressing deficiencies can improve DAO activity.
Yes. Many IBS-like symptoms overlap with histamine intolerance.
Yes. We offer at-home phlebotomy blood draws across multiple UK locations.
Testing is performed in UKAS-accredited laboratories using validated enzyme assays.
Results are usually available within 10 business days.
A GP consultation is optional, but recommended if results are low or symptoms persist.
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