Latest findings on Japanese cedar pollinosis and its treatment

Current Status of Japanese Cedar Pollinosis in Japan

Cedar pollen allergies, affecting about 40% of Japanese people, are considered a "national illness," and cases are increasing even among children. They significantly reduce academic performance, work productivity, and sleep quality, leading to problems like decreased concentration and "presenteeism" (being at work but unable to perform at full capacity) due to drowsiness. It is estimated that these issues cause annual productivity losses in Japan on the scale of hundreds of billions to one trillion yen.
Allergic rhinitis is also associated with asthma, atopic dermatitis, and food allergies, and it is important to view it as part of systemic allergies.

🌸 Treatment for Cedar Pollen Allergy and "Preventive Oral Medication Starting Two Weeks in Advance"

Treatment consists of the following four pillars.
Allergen avoidance
2) Pharmacotherapy
3) Initial therapy (preventive medication)
4) Sublingual Immunotherapy (SLIT)

"Early treatment" is particularly important. Starting a second-generation antihistamine 1 to 2 weeks before pollen dispersal can suppress nasal inflammation early and alleviate symptoms during the season.

Bilasstin is known as a drug with low drowsiness and high safety. Fexofenadine is also highly safe and is characterized by not hindering daytime activities.

What is Sublingual Immunotherapy (SLIT)?

This is the only treatment that aims to improve constitution (disease-modifying effect) by gradually acclimatizing the body to small amounts of allergens.
Estimated number of participants in Japan
Cedar SLIT: Approximately 400,000 to 600,000 people
Dust mite SLIT: Approximately 500,000 to 700,000 people
(Repeats included. Estimated that over 1 million people have undergone treatment.)

There are no official, precise statistics, but these are estimates from academic reviews and post-market data.

🌈 SLIT's effects and long-term prognosis

SLIT has been shown to be effective and have disease-modifying effects in many studies.

  • Maximum effect can be obtained with continuous use for 3 years or more.
  • In many cases, symptom improvement continues for two to three years even after treatment ends.
  • Over the years, the effectiveness gradually wanes, and within a few years, approximately half of the cases experience a relapse.
  • In many cases, relapses are not as severe as before treatment.
  • It's common to see renewed effectiveness with re-treatment (resumption).
  • The side effects are mainly mild oral discomfort, and the safety is high.

SLIT for cedar pollen allergies is expected to reduce the risk of future severe symptoms and asthma, and its effectiveness has been confirmed in Japanese children.

Child SLIT

It is a highly effective and safe treatment for children, similar to adults.
Whether sufficient treatment duration (3 years or more) could be continued most affects the long-term prognosis.

Summary

Cedar pollen allergy is a disease that greatly affects quality of life and productivity.
It is important to choose a treatment that is tailored to each patient by combining medication, initial treatment, and sublingual immunotherapy.
In particular, sublingual immunotherapy has the potential to reduce the risk of future asthma and prevent its severity, making it a promising treatment option from a long-term perspective.

References

Matsushita R, et al. SLIT in Pediatric Cedar Pollinosis. Pediatr Allergy Immunol.
Ohashi-Doi K, et al. Japanese Cedar Pollen Allergens in Japan. Curr Protein Pept Sci. 2022.
Penagos M, Durham SR. Allergen Immunotherapy for Long-Term Tolerance and Prevention. JACI. 2022.
Gotoh M, et al. Evolution of SLIT for Cedar Pollinosis. Allergol Int. 2024.
Penagos M, Durham SR. Duration of Allergen Immunotherapy. Curr Opin Allergy Clin Immunol. 2019.
Masuyama K, et al. HDM SLIT in Japanese Children. Allergy. 2018.
Nomura Y, et al. Long-Term SLIT Drops Study. Allergol Int. 2021.
Yonekura S, et al. Disease-Modifying Effect of Cedar SLIT Tablets. JACI Pract. 2021.
Hashiguchi K, et al. Bilastine Chamber Study. Allergol Int. 2017.
Kitamura Y, et al. Preseasonal Antihistamine Study. Acta Otolaryngol. 2012.
Dake Y, et al. Antihistamine Eye Drops Study. Allergol Int. 2006.