What is an allergy?
An allergy is a condition in which the immune system overreacts to a normally harmless substance (such as pollen, dust mites, food, or medication), causing adverse symptoms in the body. Symptoms can appear in any organ of the body, including the nose (sneezing, runny nose), eyes (itching, tearing), skin (hives, eczema), bronchi (cough, asthma), and digestive system (abdominal pain, diarrhea).
Sneezing, runny nose, stuffy nose
Allergic rhinitis due to pollen, dust mites, house dust
→ Hay fever, perennial rhinitis
Hives, itchy skin
Sudden welts. Caused by food, medication, stress, or unknown reasons.
→ Hives
Symptoms caused by food
Swollen lips, hives, abdominal pain, throat discomfort
→ Food allergy
Rash, itching after taking medication
Rash, fever, and itching appear after starting medication
→ Drug allergy
Itchy eyes, tearing, redness
Allergic conjunctivitis due to pollen or house dust
→ Hay fever
Unsure what the allergy is
Want to identify the cause. 39 items can be checked at once with a blood test.
→ View39 test
Hay fever (seasonal allergic rhinitis)
Hay fever is an allergic reaction to pollen that disperses during specific seasons, and approximately 40% of Japanese people are said to have cedar pollen allergy. The main symptoms are sneezing, runny nose, stuffy nose, and itchy eyes.
Main pollen dispersion periods (Kanto region)
Pollen
Dispersion period
Cedar
February to April (peak in March). The biggest cause of hay fever.
Cypress
March to May (peak in April). Approximately 70% of cedar pollen allergy sufferers also react to cypress.
Gramineae (orchard grass, etc.)
May to August. Common in grasslands in parks and riverbeds.
Ragweed, mugwort
August to October. Cause of autumn hay fever.
Treatment for hay fever
Early treatment (proactive treatment)
By starting antihistamine medication approximately two weeks before the pollen season begins, symptoms during the season can be significantly reduced. This is especially recommended for those who experience severe symptoms every year.
Second-generation antihistamines
Fexofenadine, bilastine, desloratadine, rupatadine, etc. Non-drowsy medications are common. Effective for sneezing, runny nose, and itchy eyes.
Nasal steroids
Nasal spray steroids (mometasone, etc.). Most effective for nasal congestion. Systemic side effects are almost non-existent due to local action.
Anti-leukotriene drugs
Montelukast, etc. Effective for nasal congestion. Often used in combination with antihistamines.
Eye drops
Anti-allergy eye drops (olopatadine, etc.). For itchy eyes and redness.
💡 "Hay fever also causes skin irritation" - Our clinic can treat both at the same time.
During pollen season, not only the nose and eyes, but also facial and neck skin irritation and itching (pollen dermatitis) can occur. Our clinic can prescribe both internal medicine (medication for runny nose and itchy eyes) and dermatology (topical medication for skin irritation) at the same time, allowing us to treat systemic symptoms caused by pollen in a single visit.
Perennial allergic rhinitis
If you experience sneezing, runny nose, and nasal congestion year-round regardless of the season, you may have perennial allergic rhinitis caused by dust mites, house dust, pet dander (dogs, cats), or mold.
Symptoms are severe when waking up in the morning (caused by dust mites in bedding).
Worsens during cleaning or when making/unmaking the bed.
Symptoms started after getting a pet.
Worsens when using air conditioning (mold/dust mites in the filter).
Treatment typically involves antihistamines and nasal steroids, similar to hay fever. In addition, environmental improvements (dust mite covers for bedding, frequent cleaning, air conditioner filter cleaning, appropriate humidity control) are important. The View39 test is useful for identifying the causative allergen.
Hives and Allergies
Hives are sudden red welts (raised rashes) that appear on the skin and are accompanied by severe itching. A characteristic feature is that individual welts usually disappear within 24 hours without leaving a trace.
Acute hives
Within 6 weeks of onset. May be triggered by food, medication, or infection.
Chronic hives
Recurrent for more than 6 weeks. The cause is often unknown (chronic idiopathic urticaria). Autoimmune mechanisms are involved.
Physical hives
Triggered by physical stimuli such as cold, heat, sunlight, pressure, or vibration.
Treatment primarily involves regular intake of second-generation antihistamines. For chronic hives, it is important to "continue taking the medication for a certain period even after the symptoms disappear," rather than just "taking it when symptoms appear," to prevent recurrence. For intractable cases, increasing the dosage of antihistamines or omalizumab (Xolair: anti-IgE antibody) may be an option.
⚠️ Most cases of hives are "idiopathic" - but they can still be treated.
About 70-80% of chronic hives are "idiopathic," meaning the cause cannot be identified. This does not mean that treatment is impossible; most people can be controlled with appropriate use of antihistamines.
Food Allergy
Food allergy occurs when an immune reaction occurs after consuming specific foods, leading to symptoms in the skin (hives), digestive system (abdominal pain, vomiting, diarrhea), respiratory system (throat discomfort, difficulty breathing), and systemically (anaphylaxis).
Age
Main causative foods
Infants/Toddlers
Chicken eggs, milk, and wheat are the top three causes. Tolerance often develops as they grow (they become able to eat these foods).
School-age children to adults
Crustaceans (shrimp, crab), fruits (kiwi, banana, peach), nuts, wheat, buckwheat, fish. Adult food allergies are less likely to resolve naturally.
Oral Allergy Syndrome (OAS)
This is a condition where people with hay fever experience itching, tingling, or discomfort in the mouth, lips, and throat after eating certain fruits or vegetables.
Cross-reactions occur because the protein structures of pollen and fruits are similar (e.g., cedar/cypress pollen → tomatoes, birch pollen → apples, peaches, cherries). Symptoms are often less likely to occur when the food is heated.
Drug Allergy / Drug Eruption
Drug allergy is a condition in which an immune reaction occurs after taking medication, resulting in a rash (drug eruption), fever, hives, abnormal blood test results, and so on.
Antibiotics (penicillin-based, cephalosporin-based) and NSAIDs (loxoprofen, etc.) are common causes.
Rashes often appear several days to two weeks after starting the medication.
Mild cases improve with discontinuation of the drug and antihistamines.
Severe drug eruptions (Stevens-Johnson syndrome, TEN) are accompanied by oral mucosal erosions, high fever, and extensive skin peeling, requiring emergency response.
If a drug eruption is suspected, discontinuing the causative drug is the top priority. At our clinic, we evaluate the rash, estimate the causative drug, and provide guidance on drugs to avoid in the future.
Anaphylaxis
Anaphylaxis is a severe condition in which an allergic reaction rapidly spreads throughout the body and can be life-threatening. It can be caused by food, medication, or bee venom.
🚨 Symptoms of anaphylaxis - call 119 immediately if these appear rapidly:
Skin:全身のじんましん・赤み・かゆみ
Respiratory:のどの腫れ・息苦しさ・喘鳴（ゼーゼー）・声のかすれ
Circulatory:血圧低下・めまい・意識がもうろう・冷や汗
Digestive:激しい腹痛・嘔吐・下痢
If these symptoms appear rapidly in multiple organs, there is a possibility of anaphylaxis, so please call 119 immediately. If you have an EpiPen (adrenaline auto-injector), use it without hesitation.
Allergy Test (View39)
View39 is a blood test that can measure IgE antibodies to 39 different allergens in a single blood draw.
It is recommended for those who "want to find out what kind of allergy they have" or "want to know if they have an allergy." It can be covered by insurance.
39 items that can be tested with View39
Inhalants (pollen) Cedar, Cypress, Alder, Birch, Orchard grass, Timothy grass, Ragweed, Mugwort
Inhalants (indoor) Japanese house dust mite, House dust, Cat dander, Dog dander, Cockroach, Moth
Inhalants (mold) Aspergillus, Alternaria, Candida, Malassezia
Food (egg/milk) Egg white, Ovomucoid, Cow's milk
Food (grains/beans) Wheat, Soybeans, Rice, Buckwheat, Peanuts
Food (seafood/meat) Shrimp, Crab, Mackerel, Salmon, Tuna, Chicken, Beef, Pork
Food (fruits/other) Kiwi, Banana, Apple, Sesame
Other Latex (natural rubber)
💡 View39 test is covered by insurance
Individuals with allergy symptoms can receive the View39 test under health insurance (approximately 5,000 yen for a 30% co-payment). Since all 39 items can be checked with a single blood draw, it is more efficient than checking each item individually. Results can be provided in approximately one week. It is also recommended for those who "feel a stuffy nose for no clear reason," "have unexplained hives," or "want to get a pet but are concerned about allergies."
