Urticaria (Hives) | Dermatology & Allergy Care in Hiroo & Ebisu, Tokyo | Yasashii Clinic

Medically Reviewed by: Takafumi Suzuki, MD — Primary Care in Dermatology, Internal Medicine & Allergology; Specialist in Anesthesiology

Written by: Yasumasa Ohno — Business Development & Content Manager, Yasashii Clinic Hiroo Shirokane

Last Updated: April 2, 2026

What You'll Learn in This Article

• What urticaria (hives) is — and the critical feature that distinguishes it from eczema

• Why most chronic hives have no identifiable cause — and why treatment still works

• The role of mast cells and histamine in every episode

• When hives become a medical emergency (anaphylaxis warning signs)

• How second-generation antihistamines and biologics manage chronic urticaria

Urticaria — commonly known as hives — is characterized by suddenly appearing, intensely itchy wheals (raised, red welts) that typically resolve within 24 hours without leaving marks. It affects up to 20% of people at some point in their lives. Whether you've had a single dramatic episode or have been living with recurring hives for months, effective treatment exists — and knowing when the situation is urgent can be life-saving.

Table of Contents

1. What Is Urticaria (Hives)?

Urticaria is defined by the sudden appearance of wheals — circumscribed, erythematous, raised areas of dermal edema — associated with pruritus (itch) and, by definition, individual lesions that resolve within 24 hours without leaving permanent skin changes. Urticaria lasting less than 6 weeks is classified as acute urticaria; persistence beyond 6 weeks defines chronic urticaria.

The "resolves within 24 hours" criterion is the single most important feature separating urticaria from other inflammatory skin conditions — if a wheal is still present after 24 hours, a different diagnosis (or urticarial vasculitis) should be considered.

Common Misconceptions

• "My allergy test was negative, so it can't be hives." Approximately 70% of chronic urticaria has no identifiable allergen — it is classified as chronic spontaneous (idiopathic) urticaria. IgE-based allergy testing is frequently negative, yet the condition is real and treatable.

• "The welt left a mark, so it's definitely hives." True urticaria leaves no residual pigmentation. Marks left behind suggest a different diagnosis.

• "OTC antihistamines are enough." For occasional acute urticaria, OTC first-generation antihistamines may provide temporary relief. For chronic or recurrent urticaria, second-generation prescription antihistamines, dose optimization, and sometimes biologics offer significantly better control.

2. Symptoms — Wheals, Angioedema, and Anaphylaxis

Wheals (Hives)

• Sudden onset of circumscribed, raised, erythematous (red) or pale center plaques

• Intensely pruritic (itchy)

• Variable size: a few millimeters to several centimeters; may coalesce into large geographic patterns

• Resolve completely within 24 hours — hallmark feature

• May recur in the same or different locations

Angioedema Deep swelling of the dermis, subcutaneous tissue, or mucosa, often occurring alongside or instead of wheals:

• Common sites: eyelids, lips, tongue, throat, hands, genitalia

• Associated with pain or burning rather than itch

• Resolves over 24–72 hours

• Laryngeal (throat) angioedema is a medical emergency — airway compromise is possible

Anaphylaxis Systemic, life-threatening hypersensitivity reaction involving urticaria/angioedema plus one or more of:

• Respiratory: dyspnea, stridor, wheezing

• Cardiovascular: hypotension, dizziness, loss of consciousness

• Gastrointestinal: nausea, vomiting, abdominal cramps

If anaphylaxis is suspected: call 119 immediately.

"About 30 minutes after eating shrimp at dinner, I noticed welts spreading across my chest and my throat felt strangely tight. I took an antihistamine and it settled — but I was scared. Could it happen again, and worse?" This scenario — urticaria with subtle throat symptoms after food exposure — warrants urgent allergy evaluation, epinephrine auto-injector (EpiPen®) prescription, and a clear anaphylaxis action plan.

3. Causes: Allergic, Non-Allergic, and Idiopathic

Allergic (IgE-mediated)

• Foods: shellfish, fish, wheat, eggs, dairy, tree nuts, fruits (peach, kiwi)

• Drugs: NSAIDs (aspirin, ibuprofen), penicillin and other antibiotics, contrast media

• Insect venom: bees, wasps, ants

• Latex (natural rubber): gloves, balloons

• Animal dander

Non-allergic (direct mast cell activation)

• Physical urticaria: dermographism (skin writing), cold, heat, solar, pressure, exercise-induced

• Cholinergic urticaria: triggered by sweating (exercise, hot bath, emotional stress) — characteristically small wheals

• Contact urticaria: immediate reaction at contact site without systemic IgE sensitization

Chronic Spontaneous (Idiopathic) Urticaria The most common form in clinical practice — approximately 70% of chronic urticaria cases have no identifiable cause. An autoimmune mechanism involving IgG autoantibodies against the high-affinity IgE receptor (FcεRI) or against IgE itself is implicated in a significant proportion.

Secondary Urticaria Associated with: viral infections (common cold, COVID-19), parasitic infection, thyroid disease (Hashimoto's), systemic lupus erythematosus, lymphoma.

4. The Mechanism: Mast Cells and Histamine

The final common pathway of urticaria, regardless of trigger, is mast cell degranulation and histamine release.

1. Mast cell activation: Via IgE crosslinking (allergic), direct receptor stimulation (physical, drug), or autoantibody-mediated activation (chronic spontaneous urticaria)

2. Mediator release: Histamine, prostaglandins, leukotrienes, and tryptase are released from mast cell granules

3. Vascular response: Histamine binds H1 receptors on dermal blood vessels → vasodilation (redness) + increased vascular permeability (plasma leakage into dermis → wheal)

4. Itch signal: Histamine activates H1 receptors on sensory C-fibers → intense pruritus

Why wheals resolve: Released histamine is rapidly metabolized. If the stimulus for mast cell activation is removed (allergen cleared, physical trigger ends), new degranulation stops and wheals resolve.

Why antihistamines work: Second-generation H1 antihistamines competitively block histamine at the H1 receptor, preventing vasodilation, plasma leakage, and itch. They do not prevent mast cell degranulation — hence why trigger avoidance remains important.

5. How to Tell Hives Apart from Similar Conditions

Key clinical test: Mark an active wheal with a pen — if it is still present 24 hours later, urticaria is an unlikely diagnosis and vasculitis workup should be considered.

6. Diagnosis: History, Examination, and Allergy Testing

Physical Examination Assessment of wheal morphology, distribution, dermographism, angioedema presence. For physical urticaria: ice cube test (cold urticaria), exercise test, pressure test as appropriate.

Medical History (the cornerstone of urticaria diagnosis)

• Onset, frequency, duration of individual lesions

• Timing relative to meals, medications, exercise, bathing, stress

• Full medication list — including NSAIDs, ACE inhibitors (can cause angioedema), OTC supplements

• Dietary diary — particularly for acute episodes

• Past medical history: thyroid disease, autoimmune conditions, recurrent infections

• Anaphylaxis history — critical safety question

Laboratory Tests

• Complete blood count, CRP: screen for infection, eosinophilia

• Thyroid function, anti-thyroid antibodies: thyroid autoimmunity is associated with chronic spontaneous urticaria

• Antinuclear antibody (ANA): screen for systemic autoimmune disease

• Total IgE and specific IgE panel: guided by clinical suspicion — positive results must be interpreted in clinical context

• Skin prick testing: for specific allergen confirmation

• Physical urticaria tests: dermographometer, ice cube test, exercise challenge

Your First Visit — Step by Step

Book via LINE (24/7): https://line.me/R/ti/p/@744yxkjg
or call: +81-3-6456-4990
  ↓
Complete intake form — include details of recent meals, medications, timeline
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Consultation — approx. 25–35 minutes
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Allergy testing (blood draw) if indicated
  ↓
Prescription + urticaria diary guidance / Payment

Bring: Insurance card, current medications list, any dietary or symptom diary you've kept.

7. Treatment — Antihistamines, Biologics, and Avoidance

Trigger Avoidance — foundational For identified triggers (specific foods, NSAIDs, physical factors): strict avoidance is the priority.

Second-Generation H1 Antihistamines — Insurance covered; first-line treatment Non-sedating antihistamines (bilastine, fexofenadine, cetirizine, olopatadine, loratadine) taken daily — not only when symptomatic. Key principles:

• Take every day for chronic urticaria, even on symptom-free days

• Standard dose initially; if insufficient, dose can be increased up to 4× standard dose (guideline-supported)

• Different agents can be tried if one is ineffective

H2 Antihistamines (adjunctive) Adding famotidine to an H1 antihistamine may provide additional benefit through complementary receptor blockade.

Omalizumab (Xolair®) — Insurance covered for chronic spontaneous urticaria refractory to antihistamines A monoclonal antibody targeting IgE — reduces mast cell sensitivity to IgE-mediated activation. Administered as a subcutaneous injection every 4 weeks. Clinical trials demonstrate rapid, high-efficacy response in a significant proportion of patients with treatment-refractory chronic urticaria. Remarkable efficacy even in IgE-negative, idiopathic urticaria.

Short-course oral corticosteroids — Insurance covered; acute severe cases only For severe acute urticaria or angioedema not responding to antihistamines. Not appropriate for long-term chronic urticaria management.

Epinephrine Auto-injector (EpiPen®) — Prescription Prescribed for patients with a history of anaphylaxis or high anaphylaxis risk. We provide injection technique training at the time of prescription.

8. How Long Does Recovery Take?

• Acute urticaria (identified trigger): Resolution expected within 1–2 weeks of trigger avoidance + antihistamine treatment

• Chronic spontaneous urticaria: 50% achieve spontaneous remission within 1 year; 20% have persistent disease at 5 years. Ongoing antihistamine management is required throughout.

• Omalizumab responders: Meaningful symptom reduction typically within 4–8 weeks; some patients achieve complete remission

The goal is not immediate cure but sustained symptom control with minimal medication burden — progressively stepping down treatment as disease activity decreases.

9. Everyday Management

During a flare

• Cool (not cold) compresses on affected areas reduce itch temporarily

• Avoid scratching — scratch stimulation triggers further mast cell degranulation and spreads wheals

• Avoid hot baths, alcohol, and vigorous exercise during active episodes — all promote histamine release

• Take prescribed antihistamines consistently

Daily habits for chronic urticaria

• Take antihistamines at the same time each day — consistency matters more than timing relative to symptoms

• Keep a urticaria diary: date/time, symptom intensity (1–10 scale), food eaten, medications taken, activity, stress level

• Avoid NSAIDs for pain/fever — use acetaminophen instead

• Moderate alcohol intake

• Manage stress: walks around Arisugawa-no-miya Memorial Park, regular sleep, structured relaxation

10. Risks of Leaving Urticaria Unmanaged

Anaphylaxis risk: Patients with food-triggered or drug-triggered urticaria may progress to anaphylaxis on subsequent exposure. Not every episode of urticaria warns you — the next one may be systemic. Epinephrine auto-injector access and an action plan are essential.

Missed underlying diagnosis: Urticaria as a presenting symptom of thyroid disease, autoimmune disease, or occult infection is frequently missed when patients self-treat with OTC antihistamines without investigation.

Urticarial vasculitis: Misidentified as ordinary urticaria, vasculitis can cause renal, joint, and organ involvement if untreated.

Chronic QOL impact: Chronic itching causes sleep deprivation, anxiety, depression, and significant impairment in work and social functioning. The psychological burden of chronic urticaria rivals that of psoriasis and eczema in severity studies — it deserves medical attention proportionate to that burden.

11. Who Is at Higher Risk?

• People with food allergies (particularly shellfish, tree nuts, wheat): anaphylaxis risk assessment and epinephrine prescription are important

• Women aged 20–40: chronic spontaneous urticaria is more common in women, possibly related to autoimmune predisposition

• People taking NSAIDs regularly: NSAIDs are among the most common drug triggers of urticaria; switching to acetaminophen is often beneficial

• Patients with autoimmune thyroid disease: association with chronic spontaneous urticaria is well-established

• Expats and international residents in Hiroo and Shirokane: unfamiliar Japanese foods (fermented products, specific seafood, certain food additives) and environmental changes can trigger new urticaria; English-language allergy care is available at our clinic

12. When to Seek Care — Checklist

Emergency — call 119 immediately:

• Throat tightness, voice change, difficulty breathing

• Dizziness, low blood pressure, or loss of consciousness with hives

• Rapid generalized spread of hives with any systemic symptom

Urgent — same day or next day:

• ☑ Widespread rapidly spreading hives with lip/eyelid/tongue swelling

• ☑ History of anaphylaxis with any food or drug

• ☑ Hives occurring with every exposure to a specific food or drug

Routine — within a few days:

• ☑ Hives occurring more than twice per week for more than 6 weeks

• ☑ OTC antihistamines are not controlling symptoms adequately

• ☑ Individual wheals persist longer than 24 hours or leave marks

• ☑ Children with recurrent hives of unknown cause

13. Trigger Tracking and Relapse Prevention

Urticaria Diary — What to Record

Sharing this diary at your follow-up appointment enables us to identify patterns that a single consultation cannot reveal.

Avoiding known triggers in Tokyo

• Check ingredient labels carefully when shopping at supermarkets in Hiroo and Ebisu — shellfish, wheat, and nut derivatives are present in many processed foods

• When dining at restaurants along Hiroo Promenade or near Daikanyama, communicate allergens clearly to staff; menus may not list all ingredients

• Replace NSAIDs with acetaminophen for routine pain management

• Stay cool during the summer months when walking near Shizen-kyoiku-en or along Platinum-dori — heat-triggered and cholinergic urticaria flare in warm weather

14. Allergy & Dermatology Care at Yasashii Clinic Hiroo Shirokane

English-Friendly, Integrated Allergy and Dermatology Care

We regularly see patients from the international community in Hiroo, Minami-Azabu, Shirokane, and Ebisu for urticaria evaluation and management. English consultations are available. We are accustomed to taking detailed dietary histories, reviewing ingredient lists, and explaining allergy test results in a way that is clear and actionable — in English.

We accept Japanese national health insurance and self-pay. For international insurance plans, we provide documentation for reimbursement claims.

Why Our Clinic Is Particularly Well-Suited for Urticaria

Urticaria sits at the intersection of dermatology, allergology, and internal medicine — all three of which are practiced at our clinic. Dr. Suzuki's background in critical care and internal medicine means we are alert to the systemic presentations of urticaria (anaphylaxis, vasculitis, systemic autoimmune disease) and can manage these dimensions alongside the dermatological aspect of care.

"Chronic hives is not 'just a skin problem.' The impact on sleep, work, and mental health is profound — and there are effective treatment options that many patients are not yet aware of."

For cases requiring omalizumab management monitoring, complex immunological workup, or anaphylaxis risk assessment beyond our scope, we maintain referral pathways to Tokyo Metropolitan Hiroo Hospital, Japanese Red Cross Medical Center, Kitasato University Kitasato Institute Hospital, and The Institute of Medical Science Hospital (University of Tokyo).

Access & Hours

• 5 min walk from Hiroo Station (Tokyo Metro Hibiya Line, Exit 2)

• 10 min walk from Ebisu Station (JR / Tokyo Metro)

• 13 min from Shirokanedai and Shirokane-Takanawa Stations

• Parking available

Opening Hours: Monday: 16:00–20:00 | Wednesday & Thursday: 10:00–14:00 / 16:00–20:00 Saturday & Sunday: 10:00–18:00 | Public Holidays: 10:00–14:00 Closed: Tuesday, Friday Please check the official website or call for the latest schedule.

Related diseases

• Atopic Dermatitis

• Contact Dermatitis

Other related

• Dermatology Services

• Allergology

• About Us & Our Physicians

Book via LINE (24/7)

Phone: +81-3-6456-4990

15. Summary

• Urticaria is defined by wheals that resolve within 24 hours without leaving marks — this single feature differentiates it from almost all other inflammatory skin conditions

• Most chronic urticaria (>6 weeks) is idiopathic — negative allergy tests do not mean the condition isn't real or treatable

• Daily second-generation antihistamines are the backbone of treatment; omalizumab (Xolair®) is available for antihistamine-refractory chronic urticaria

• Throat swelling, breathing difficulty, or systemic symptoms with hives = potential anaphylaxis = 119 immediately

• Recurring hives warrant a systematic clinical evaluation, not just OTC antihistamine use

English FAQ

Q1. What causes urticaria (hives)? Causes include allergic reactions (food, drugs, insect venom, latex), physical triggers (cold, heat, pressure, exercise), infections, and autoimmune mechanisms. About 70% of chronic urticaria has no identifiable cause (chronic spontaneous urticaria).

Q2. Is urticaria contagious? No. Urticaria is not an infection and cannot be transmitted to others. It is an immune-mediated skin reaction. If urticaria follows a viral illness, the virus may have been contagious — but the hives themselves are not.

Q3. How long does urticaria treatment take? Acute urticaria with an identified trigger resolves within 1–2 weeks of trigger removal and antihistamine treatment. Chronic urticaria requires ongoing daily antihistamine management; about 50% of patients achieve spontaneous remission within one year.

Q4. Are OTC antihistamines enough? For occasional mild acute hives: possibly. For chronic, recurrent, or severe urticaria: prescription second-generation antihistamines at optimized doses provide significantly better control. If hives are recurring, a medical evaluation to rule out anaphylaxis risk and systemic causes is important.

Q5. When is it an emergency? Call 119 immediately if urticaria is accompanied by throat tightness, voice change, difficulty breathing, dizziness, low blood pressure, or loss of consciousness.

Q6. What is the difference between urticaria and angioedema? Urticaria involves wheals in the superficial dermis. Angioedema is deeper swelling in the subcutaneous tissue, typically affecting the face (lips, eyelids, tongue) and sometimes the throat. They frequently occur together. Throat angioedema is a medical emergency.

Q7. What is omalizumab (Xolair®) and who should consider it? Omalizumab is a biologic medication (anti-IgE antibody) that reduces mast cell sensitivity. It is approved in Japan for chronic spontaneous urticaria that has not responded adequately to antihistamines, even at increased doses. It is administered by subcutaneous injection every 4 weeks and is covered by Japanese health insurance for qualifying patients.

Q8. Do you see foreign patients? Is English available? Yes — we regularly treat urticaria in expats and foreign residents in Hiroo, Minami-Azabu, Shirokane, and Ebisu. English is available.

Q9. Is urticaria treatment covered by Japanese health insurance? Yes. Consultations, antihistamine prescriptions, and blood allergy testing are covered. Omalizumab is covered for chronic spontaneous urticaria refractory to antihistamines (with prior authorization). EpiPen® (epinephrine auto-injector) is covered by prescription for patients at risk of anaphylaxis.

Q10. Can I have an online consultation for urticaria? Yes — follow-up consultations and chronic urticaria monitoring are available online. For first visits, anaphylaxis risk assessment, or allergy testing, an in-person visit is recommended.

Author:Name: Yasumasa Ohno
Role: Business Development & Content Manager, Yasashii Clinic Hiroo Shirokane

Medical Reviewer:
Name: Takafumi Suzuki, MD
Credentials: Specialist in Anesthesiology (Japan Board of Anesthesiology)

Affiliations:
- Japanese Society of Anesthesiologists (JSA)
- Japanese Society of Internal Medicine (JSIM)
- Japanese Society of Intensive Care Medicine (JSICM)
- Japanese Association for Cardiovascular Anesthesia (JACA)
Clinical Background: Critical care medicine, perioperative management, pain medicine; primary care in internal medicine, dermatology, allergology, and sleep medicine (OSA)

Operating Organization:
Name (Japanese): やさしいクリニック 広尾 白金
Name (English): Yasashii Clinic Hiroo Shirokane
Address: O-KA Building 3F, 2-31-3 Ebisu, Shibuya-ku, Tokyo 150-0013, Japan

Tel: +81-3-6456-4990
URL: https://yasashii-clinic.jp
Booking: https://line.me/R/ti/p/@744yxkjg (LINE, 24/7)
Specialties: Internal Medicine / Dermatology / Allergology / Pain Clinic

Opening Hours:
Monday : 16:00–20:00
Tuesday : Closed
Wednesday : 10:00–14:00 / 16:00–20:00 (2nd & 4th Wed: morning only)
Thursday : 10:00–14:00 / 16:00–20:00
Friday : Closed
Saturday : 10:00–18:00
Sunday : 10:00–18:00
Public Holidays: 10:00–14:00

* Hours subject to change. Please check the official website for the latest schedule.

Access:
5 min walk from Hiroo Station (Tokyo Metro Hibiya Line, Exit 2)
10 min walk from Ebisu Station (JR / Tokyo Metro)
13 min walk from Shirokane-Takanawa / Shirokanedai Station
Languages: Japanese (primary), English available
Online Consultation: Available

Payment: Cash / Credit cards accepted
Last Updated: 2026-04-02

Medical Disclaimer:
This article is for general informational purposes only and does not constitute medical advice, diagnosis, or treatment. The information provided reflects current medical knowledge at the time of writing. Individual symptoms and conditions vary; please consult a qualified physician for personal medical advice. If you are experiencing an emergency, contact emergency services immediately. This content has been medically reviewed by a licensed physician.