Sneezing through a spring trip to Tokyo while everyone around you wears a mask? Japanese cedar, sugi, is the pollen behind Japan's national hay fever season. Our test checks IgE to Cry j 1, its main protein, as part of 300 allergens and allergen components, next to cypress and juniper from the same family.
Japanese cedar (Cryptomeria japonica) is not a true cedar. It is a conifer in the cypress family, and Japan planted it on a huge scale after the Second World War. Those forests now release enormous amounts of pollen every spring.
More than a third of people in Japan have sugi pollen hay fever, and it is often called the national affliction. Pollen forecasts run alongside the weather on TV, and masks and glasses are a common sight from February to April.
Sugi forests do not exist in Finland, Ireland, the Netherlands or Germany, so at home this pollen plays almost no role. It matters for people who travel to or move to Japan in spring, which is exactly when the pollen load is at its highest.
It also matters through the family link. Cry j 1 is a pectate lyase that closely resembles the main allergens of cypress (Cup a 1) and juniper. If your blood shows IgE to Mediterranean cypress, it may well recognise sugi too, and the other way round.
The pattern is classic hay fever: bursts of sneezing, a runny or blocked nose, and itchy, watery eyes. Because the season lasts several months, symptoms can be intense and drawn out.
Many visitors notice it for the first time a few days into a trip. Symptoms that start in Japan in March and ease after the flight home are a typical story.
From a finger-prick sample, the lab measures IgE to Cry j 1, the main Japanese cedar pollen protein (a molecular component), as part of 300 allergens and allergen components. There is no whole sugi extract on the panel. Italian cypress, Arizona cypress (Cup a 1) and mountain cedar sit on the same report, so you see the whole cypress family side by side.
A positive result means your blood shows IgE to Japanese cedar pollen. That is sensitisation, not a diagnosis. Each value gets a class from Negative to Very high, to discuss with a doctor, ideally before your next spring trip.
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One finger-prick sample checks IgE to 300 allergens and allergen components, from birch and peanut to cat and house dust mite. Post it to the lab, and about 5 days after it arrives you get a value for every one. Our plain-English guide shows you how to read them. €399 in total, €1.33 per allergen.
Sugi pollen is usually in the air from February to April, peaking in March. It starts earlier in the south and later in the north. Japanese cypress (hinoki) follows into April and May. Hokkaido and Okinawa have very little sugi.
Japan's spring pollen load is dominated by sugi, which hardly exists in northern Europe. If you are sensitised to it, or to related cypress pollen, you may only notice it there. A test shows whether your blood has IgE to Cry j 1.
No. Despite the name, Cryptomeria japonica belongs to the cypress family, not the true cedars (Cedrus). That is why its main allergen resembles those of cypress and juniper.
If you have had symptoms there before, testing at home first gives you and a doctor something concrete to plan with. IgE is measurable all year, so you can test in autumn or winter, weeks before you fly.
