Eosinophils: high or low results, normal range and absolute count

An eosinophil count is part of every complete blood count (CBC), reported as a percentage of your white cells and as an absolute eosinophil count, the number in a set volume of blood. When eosinophils are high, the usual reasons are allergic conditions such as hay fever, asthma and eczema, a reaction to a medicine, or a parasite infection. A mild rise often fits a known allergy; a large or lasting rise is what a doctor looks into further.

What eosinophils are

Eosinophils are white cells that defend against parasites, take part in allergic reactions and help control inflammation. Most of them live in the body's tissues, where they can persist for weeks; in the blood they last 8 to 18 hours. So a blood count shows a small, fast-changing slice of them. They usually make up 1% to 4% of white cells.

Percentage or absolute count

Many labs flag an eosinophil percentage above about 5%, but specialists say the absolute count should be worked out before calling a result high, because the percentage moves whenever other white cells do. The absolute count is the white cell count multiplied by the eosinophil percentage: 6.0 × 10⁹/L white cells with 6% eosinophils gives 0.36 × 10⁹/L, within the usual adult range despite the raised percentage.

Normal range

Results are reported as × 10⁹/L, the SI unit, or as cells per microlitre (cells/µL); multiply by 1,000 to convert.

Both figures are MedlinePlus's. Individual labs set their own: one NHS laboratory uses 0.1 to 0.4 × 10⁹/L, another 0.0 to 0.8, and specialists note that the upper limit sits between 0.45 and 0.55 depending on the laboratory. Read your result against the range printed on your own report. For local context, 1,032 healthy Emirati citizens, mostly young adults, had an average eosinophil count of 0.17 × 10⁹/L, with a reference spread of 0.02 to 0.5.

When the count is raised, doctors describe it by size:

What a high result usually points to

• Allergic conditions. Hay fever (allergic rhinitis) and asthma often produce a mild rise. Eczema can produce a larger one when it covers much of the body.
• Medicines. Some antibiotics, including penicillins, cephalosporins and quinolones, can raise eosinophils without any symptoms, and a rise caused by a medicine can take months to clear. Interferon, laxatives containing psyllium and amphetamine-type appetite suppressants are also listed causes.
• Parasites, mainly worms that live in tissues. Strongyloides is a common one and can persist for decades after infection. Some gut parasites, such as Giardia, do not raise the count.
• Less common causes, including low adrenal function (Addison disease), inflammatory conditions such as inflammatory bowel disease, and blood disorders.

The history often points to the cause, so a doctor usually starts there: allergies, asthma, skin problems, new medicines, and where you have lived and travelled. A repeat count shows whether the rise is lasting. When a parasite is possible, specialists advise testing for Strongyloides, and a sustained count of 1.5 × 10⁹/L or more without a clear cause leads to a wider evaluation.

What a low result usually points to

Some laboratories set the lower limit at zero, so a very low count is often still within range. Eosinophils are sensitive to steroids, including the body's own cortisol, and a count near zero can be seen with steroid medicines or when the body makes too much cortisol. Alcohol intoxication can also lower it.

Eosinophils and allergy in the UAE

Allergic rhinitis, the condition behind hay fever, is a common reason for a mild rise, and it is well documented here. A survey of 1,229 adults across all seven emirates found symptoms of allergic rhinitis in at least 7%, and 89% of those also had asthma. Dust made symptoms worse for 59% and grass or pollen for 44%. Winter was the peak season, and 61% were not receiving any treatment.

So in the UAE, a mildly raised eosinophil count in someone whose nose flares with dust or in winter is a familiar picture. It is still worth raising with a doctor, who will read it alongside your symptoms.

What moves the count

• Steroid medicines, which lower it.
• Allergy seasons and flares, which can raise it.
• New medicines, especially antibiotics.
• Sample handling. In one study, eosinophil counts fell steadily in samples left at room temperature for more than 8 hours, while refrigerated samples held steady for 48 hours.

Preparing for the test

A blood count needs no fasting; if other tests in the same draw do, follow their instructions. Tell the person taking the sample about steroid medicines, antibiotics or other medicines started recently, any current allergy flare, and recent travel.

How Clare's panel handles it

In Clare's panel, the eosinophil percentage and the absolute eosinophil count are both measured by the lab, from the same full blood count sample, and linked by one calculation:

Absolute eosinophil count = white blood cell count × eosinophils % ÷ 100

Eosinophils do not feed into the inflammatory ratios Clare calculates, so they are read on their own, with your history beside them.

Price

Eosinophils are not usually sold as a test of their own; they are reported within a complete blood count. When we read public prices on 11 October 2026, a CBC cost from 35 to 149 at 7 UAE providers. VAT is rarely stated, some figures are offers or starting prices, and home collection can add a fee.

Related tests

The White Blood Cell Count (WBC) is the total the percentage is taken from. Basophils are the other white cell tied to allergic reactions. High-Sensitivity C-Reactive Protein (hs-CRP) looks at inflammation from another angle, through a protein the liver releases. For the rest of a full panel, see what to expect from a comprehensive blood test in Dubai.

Why the number means more over time

Eosinophils shift with seasons, medicines and allergy flares, so one count is a snapshot. Doctors judge a raised result partly by whether it lasts: the point at which a wider evaluation starts is a sustained count of 1.5 × 10⁹/L or more, which by definition takes more than one test. Clare is opening with a waitlist at clare.health.