Why Are Allergies So Bad in Japan — and Why Is 2026 Especially Rough?
Kafunsho Season 2026 — Post 1 of 3: Understanding why Japan's allergy season hits so hard
Post 1 of 3
Why Are Allergies So Bad in Japan — and Why Is 2026 Especially Rough?
If you've been sneezing nonstop, dealing with itchy eyes, or feeling like your head is full of wet sand — you're not imagining it.
A problem 70 years in the making
Japan's kafunsho (花粉症) season is one of the worst in the world. After World War II, Japan planted vast forests of fast-growing sugi (cedar) and hinoki (cypress) trees. As those trees matured, they began producing enormous amounts of pollen. By 2000, more than 85% of cedar trees were over 20 years old — and cedar trees older than 30 release pollen in especially large quantities.
Approximately 4.41 million hectares — roughly one-tenth of Japan's land area — is now covered by planted cedar forest. The government's goal is to reduce pollen levels by half within 30 years. Welcome news, but it doesn't help you this spring.
2026 season alert
Pollen counts in 2026 are forecast to reach 28% higher than an average year across Japan — a direct consequence of last summer's extreme heat, which promoted growth of the male flowers that produce pollen.
Why it's worse in cities like Zama and Yokohama
Even if you don't live near a forest, you're not safe. Cedar pollen can travel over 100 kilometers. Urban heat means the pollen keeps circulating and settles on buildings, clothing, and hair — then gets carried indoors through daily movement.
And if you're new to Japan: don't assume you're immune. Many expats develop hay fever after 2–3 years due to prolonged exposure. Your immune system can become sensitized over time.
What to watch for
Kafunsho symptoms go well beyond the classic runny nose and sneezing:
Itchy, watery, or red eyes
Sore throat and coughing
Headache and heaviness in the head
Fatigue and insomnia
Irritability and low mood
That last cluster — fatigue, brain fog, mood changes — is worth paying close attention to. It's exactly what we'll cover in our next post.
Up next (April 8): Could your fatigue, brain fog, or low mood actually be allergies — even without major sneezing? The answer might surprise you.
Whether this is your first kafunsho season or your fifth, we're here to help you get through it.
Partnering in your care,
Dr. Kenji Taylor, MD
Torii Health & Iris Dental and Medical
Symptoms bothering you now?
Don't wait. We can help you get ahead of this season.
Book a Visit info@toriihealth.org
www.toriihealth.org
