Skip to main content

Respiratory · London

Private FeNO asthma test in London, a 60-second breath test that changed asthma diagnosis.

A quick, non-invasive breath test that measures airway inflammation - central to modern NICE asthma diagnosis and to picking biologic-eligible patients.

A stethoscope on a clinical desk

Indicative pricing

What a private FeNO asthma test costs in London.

Indicative ranges across UK private providers.

In short

FeNO alone: £75–£150; a full asthma diagnostic bundle: £450–£900.

Test Indicative range
FeNO only £75–£150
FeNO + spirometry £180–£350
FeNO + full PFTs £400–£800
FeNO + respiratory consult £280–£550
Full asthma diagnostic bundle £450–£900
Post-biologic FeNO monitoring £75–£150

Prices vary by clinic, which studies are included, and whether a consultant review is arranged on the day.

The problem

Asthma is one label for several different diseases.

FeNO separates eosinophilic, steroid-responsive asthma from the rest - quickly, cheaply and at the mouthpiece. Pairing it with spirometry is now the modern NICE-standard first step, and it is the fastest way to know who will respond to biologics.

  • Suspected but never confirmed asthma?

    FeNO plus spirometry with reversibility is the definitive modern workup - in a single visit.

  • Poorly controlled on inhalers?

    A rising FeNO on treatment points to adherence, technique or dose - a fixable problem.

  • Considering a biologic?

    FeNO is one of the fastest markers used to screen for anti-IL-4/13 and anti-IgE eligibility.

What it shows

Find the test that matches your indication.

FeNO answers a narrow but important set of questions in asthma care. These are the questions asked most often.

  • Confirming asthma diagnosis

    A raised FeNO with compatible symptoms strongly supports an asthma diagnosis alongside spirometry.

  • Eosinophilic asthma phenotype

    FeNO is the fastest bedside marker of type-2, eosinophil-driven airway inflammation.

  • Biologic-eligibility screen

    A high FeNO helps identify patients likely to respond to anti-IL-4/13 and anti-IgE biologics.

  • Uncontrolled asthma

    A rising FeNO on treatment suggests poor adherence, wrong device or steroid under-dosing.

  • Paediatric asthma diagnosis

    FeNO is validated in children old enough to perform a steady 10-second exhalation.

  • Pre-op asthma clearance

    A quick objective marker of airway inflammation before elective anaesthesia.

  • Monitoring inhaled steroid response

    FeNO falls within days of an effective inhaled corticosteroid - a useful control check.

  • Red flags

    Acute breathlessness, silent chest, blue lips or collapse is an emergency - call 999.

FeNO options

Not all FeNO appointments are the same.

What each option on your referral is actually for.

  • FeNO only

    The standalone 60-second breath test - quick, cheap and often enough to move a diagnosis forward.

  • FeNO + spirometry

    The NICE-recommended pairing for suspected asthma: inflammation plus airflow in one visit.

  • FeNO + full PFTs

    Adds lung volumes and gas transfer when restrictive or overlap disease is on the differential.

  • FeNO + respiratory consult

    FeNO measured on the day, then interpreted face-to-face with a consultant respiratory physician.

  • Full asthma diagnostic bundle

    FeNO, spirometry with reversibility and consultant review - the definitive workup in a single visit.

  • Post-biologic monitoring

    Serial FeNO to track response to mepolizumab, benralizumab, dupilumab or omalizumab.

  • Occupational asthma pathway

    Baseline and serial FeNO around work exposure - useful when workplace triggers are suspected.

  • Paediatric FeNO (specialist)

    Delivered by clinicians experienced in coaching children through a reliable exhalation.

Safety and eligibility

Painless, non-invasive - and prep is minimal.

FeNO is one of the safest tests in respiratory medicine. A short fast, no vigorous exercise and no smoking beforehand is usually all that is asked.

  • 1-hour fast before test

    Nothing to eat for one hour before the appointment so recent food does not skew the reading.

  • Avoid exercise 1 hour before

    Vigorous exertion transiently lowers exhaled nitric oxide. Rest quietly for an hour beforehand.

  • Avoid smoking or vaping 1 hour before

    Smoke and vapour lower FeNO acutely. Please avoid both for at least an hour before the test.

  • Not affected by pregnancy

    FeNO is a passive breath test and is entirely safe at any stage of pregnancy.

  • A single elevated FeNO is meaningful

    In the right clinical context, one raised value is enough to change management - no repeat is required.

  • Steroids reduce FeNO

    Recent inhaled or oral corticosteroids can lower the reading - it helps to note what you have taken and when.

  • Nitrate-rich foods can transiently raise it

    Spinach, beetroot and processed meats can nudge FeNO upward for a few hours after eating.

  • Asthma diagnosis needs more than one test

    FeNO + spirometry (and reversibility where needed) - no single test alone confirms asthma.

  • Always share prior asthma tests

    Old FeNO, spirometry and peak-flow diaries make it possible to plot a trend rather than judge a single number.

Reading your report

A FeNO report looks like one number. Context is everything.

Whether alone or paired with spirometry, the report keeps to the same four parts.

A UK consultant respiratory physician reviewing a FeNO report

A quiet reminder

A single elevated FeNO is meaningful - but only in the right clinical context.

Ask your clinician to talk you through it at your follow-up.

  1. 01 Header

    Your details, indication and medications

    Your details, the reason for testing and every inhaler or steroid you have taken in the last 4 weeks.

  2. 02 Technique

    Device and technique

    Which analyser was used, calibration status, and whether the exhalation met ATS/ERS acceptability.

  3. 03 Findings

    FeNO value and interpretation

    Your ppb value plotted against the < 25 / 25–50 / > 50 thresholds used in modern asthma guidelines.

  4. 04 Impression

    The conclusion: read this first

    Likely eosinophilic asthma, unlikely, or intermediate - with the recommended next step. Read this first.

Recognised by major UK insurers

BupaAXA HealthVitalityAvivaWPACignaHealixBupaAXA HealthVitalityAvivaWPACignaHealixBupaAXA HealthVitalityAvivaWPACignaHealix

Frequently asked

Common questions about FeNO asthma testing.

Quick answers on cost, referrals, fasting, steroids and results.

  • What does a FeNO test actually measure?

    FeNO measures the concentration of nitric oxide in your exhaled breath, reported in parts per billion (ppb). Nitric oxide is produced by inflamed airway cells in type-2, eosinophilic inflammation - the pattern most closely linked to allergic and steroid-responsive asthma.

  • Do I need to fast before a FeNO test?

    Yes - a light one-hour fast is recommended. Nitrate-rich foods such as spinach, beetroot and processed meats can transiently raise FeNO, so avoiding food for an hour beforehand gives the cleanest reading.

  • Is FeNO safe in pregnancy?

    Completely. FeNO is a passive breath test with no radiation, no injections and no medication. It can be performed at any stage of pregnancy and is often useful for reviewing asthma control before delivery.

  • Can children have a FeNO test?

    Yes - FeNO is validated in children who are old enough to perform a steady 10-second exhalation, typically from around age 6. Paediatric cases are best done by clinicians experienced in coaching younger patients through the manoeuvre.

  • How does FeNO fit into an asthma diagnosis?

    Modern guidelines (NICE NG245, BTS/SIGN, GINA) recommend combining FeNO with spirometry - and bronchodilator reversibility where appropriate. A raised FeNO plus obstructive spirometry with reversibility is the most robust confirmation of asthma.

  • How much does a private FeNO test cost in London?

    A standalone FeNO is typically £75–£150. Paired with spirometry it is £180–£350; with full PFTs £400–£800; and inside a full asthma diagnostic bundle with a consultant review £450–£900.

  • How quickly do I get the results?

    The FeNO value is available immediately at the mouthpiece.

  • How do steroids affect FeNO?

    Inhaled and oral corticosteroids suppress eosinophilic airway inflammation and therefore lower FeNO - often within days. That is diagnostically useful: a falling FeNO on treatment suggests you are responding well to your inhaled steroid.

  • When should I see a GP or 999 urgently?

    FeNO is not for emergencies. If you have acute severe breathlessness, chest pain, blue lips, a silent chest or collapse, call 999. Rapidly worsening asthma control between appointments warrants an urgent GP or A&E review.

Related content

Looking for something else?

In practice, in London

Booking feno asthma privately in London - what actually happens

With feno asthma, the London question is usually about report turnaround and the radiologist reading it - not whether the scan is available. The wait for feno asthma on the NHS depends heavily on where you live and how urgently the referral is graded. Central and West London private clinics can normally book within a week, with imaging or a procedure slot to follow shortly after. It’s worth being honest about the reason for going private: usually it’s time, not a fundamentally different test.

In practice, a private feno asthma appointment in London means a named consultant, a proper hour in the room (or the equivalent on a video call), and a report you can actually read. Many of the imaging suites and endoscopy units used for private care sit within a mile of Harley Street or in Chelsea and Fulham, and turnaround on findings is measured in days, not weeks. For feno asthma specifically, the difference between a routine report and a sub-speciality read is where private care earns its keep.

Fit matters more than people expect. For feno asthma, the right consultant depends on what you actually need - a second opinion, a definitive diagnosis, a bridge into treatment, or reassurance that nothing’s being missed. If a test isn’t the right next step, it is worth establishing that before you book anything.