What is Urticaria (Hives)?
Urticaria, or hives, is a skin condition characterized by the sudden appearance of red, raised wheals on the skin, accompanied by intense itching. A key feature of wheals is that they disappear without a trace within a few minutes to 24 hours. It is a very common condition in Japan, estimated to affect approximately 15-20% of people in their lifetime, meaning 1 in 5 or 6 individuals.
While often thought to be caused by "food or medicine," about 70-80% of chronic urticaria cases are "idiopathic," meaning the cause cannot be identified. Even without knowing the cause, modern treatments can control symptoms with a high degree of success.
The biggest misconception about hives: "Dietary restrictions will cure it" is incorrect.
In cases of chronic urticaria where the cause cannot be identified, dietary restrictions do not lead to improvement. Self-imposed elimination diets only disrupt nutritional balance. Unless specific allergens are confirmed, the basic approach is to continue a normal diet while undergoing drug treatment.
Classification of Urticaria
Classification by Duration
| Classification | Duration | Characteristics |
|---|---|---|
| Acute Urticaria | Within 6 weeks | Often caused by infections, food, or medications |
| Chronic Urticaria | Lasts 6 weeks or more | Approximately 70-80% are idiopathic (unknown cause) |
Classification by Cause/Trigger
| Type | Characteristics |
|---|---|
| Idiopathic | Unknown cause, most common, with diurnal variations |
| Physical | Triggered by pressure, cold, heat, sunlight, vibration, water, etc. |
| Cholinergic | Appears with sweating due to exercise, bathing, emotional stress; small erythema |
| Food-induced/Drug-induced | Triggered by specific foods/drugs (direct cause is clear) |
| Allergic | IgE-mediated, onset immediately after contact/ingestion of causative substance |
| Exercise-induced | Triggered by a combination of food + exercise (Food-dependent exercise-induced anaphylaxis) |
| Contact | Appears when specific substances touch the skin |
| Angioedema | Swelling deeper than wheals, affects lips, eyelids, tongue |
Symptoms of Urticaria
Characteristics of Typical Wheals
- Sudden appearance, intense itching
- Well-defined redness, center may appear as normal skin (bluish swelling)
- Size ranges from a few mm to over 10 cm
- Disappears without a trace within 24 hours
- May appear and disappear repeatedly throughout the day
- When one spot disappears, another appears elsewhere
Conditions Similar to Wheals but Different
| Condition | Difference from Urticaria |
|---|---|
| Eczema/Dermatitis | Leaves marks, lasts for several days or more |
| Erythema Multiforme | Target-like erythema, lasts for several days |
| Urticarial Vasculitis | Wheals last for more than 24 hours, leaves pigmentation |
| Insect Bites | Sting mark in the center, localized |
Anaphylaxis Requires Emergency Response
If you experience any of the following symptoms, call for emergency medical help (119).
While urticaria alone is usually not life-threatening, anaphylaxis is an emergency. Do not hesitate to call 119 and use an EpiPen.
- Difficulty breathing, wheezing (laryngeal edema, bronchospasm)
- Swelling of eyelids, lips, tongue (angioedema)
- Hoarseness, difficulty speaking
- Decreased blood pressure, altered consciousness
- Severe abdominal pain, vomiting
- Widespread flushing
- Rapid onset after eating, insect bite, or medication administration
Investigation for Causes in Suspected Chronic Urticaria
For urticaria lasting longer than 6 weeks, it is crucial to rule out underlying diseases.
| Related Disease | Tests to Confirm |
|---|---|
| Thyroid disease (especially Hashimoto's thyroiditis) | TSH, Anti-thyroglobulin antibody, Anti-TPO antibody |
| H. pylori infection | Urea breath test, Stool antigen test |
| Chronic infections (sinus, dental caries, urinary tract) | Symptom history, further investigation as needed |
| Collagen disease/Autoimmune disease | Antinuclear antibody, Complement |
| Malignant tumor (rare) | Health check-up, symptom confirmation |
| Parasitic infection | Blood eosinophils, Stool test |
Allergy Testing
- Specific IgE test: Selective testing for food and inhalant allergens
- View39 test: Batch testing for 39 types of allergens with a single blood draw (covered by insurance)
- Total IgE: Overall assessment of allergic predisposition
- Skin prick test: Referral to a specialist institution if necessary
Limitations of Allergy Testing
In chronic idiopathic urticaria, allergy tests are rarely positive. The global guideline focuses on appropriately controlling symptoms rather than identifying the cause.
Treatment (Gradual Approach Centered on Antihistamines)
Global urticaria guidelines (EAACI, Japanese Dermatological Association) recommend a staged treatment approach centered on second-generation antihistamines.
Step 1: Second-generation antihistamines (standard dose)
| Medication | Characteristics |
|---|---|
| Bilastine (Bilonoa) | Very low drowsiness, once daily |
| Fexofenadine (Allegra) | Low drowsiness, twice daily |
| Desloratadine (Desalex) | Low drowsiness, once daily |
| Rupatadine (Rupafin) | Also has anti-PAF action, powerful, once daily |
| Olapadine (Allegra) | Strong effect, some drowsiness |
Step 2: Increase antihistamine dose up to 4 times
If the effect is insufficient, the same drug can be increased up to 4 times the dose under medical supervision. This method is recommended by international guidelines.
Step 3: Add Omalizumab (Xolair)
A Game-Changer for Refractory Chronic Urticaria
Omalizumab, an anti-IgE antibody, is covered by insurance for chronic idiopathic urticaria in patients 12 years and older who have had insufficient results with antihistamines. Administered as a subcutaneous injection once every 4 weeks, it is highly effective in about 70% of patients. Introduction and maintenance can be done at our clinic.
Step 4: Cyclosporine, etc.
If the above treatments are insufficient, immunosuppressants are an option. We will coordinate with specialist institutions for this.
During Acute Phases and Severe Symptoms
- Short-term oral steroids (prednisolone): severe acute urticaria
- Intravenous antihistamines/drips: emergency situations
- Angioedema/anaphylaxis: intramuscular epinephrine, steroids
About Topical Medications
Urticaria is a condition caused by histamine reactions within the body, not a surface skin problem. Therefore, topical medications (steroid ointments, etc.) are generally ineffective. Their use should be limited to temporary relief with anti-itch creams.
Goals and Duration of Chronic Urticaria Treatment
- Elimination of symptoms is the treatment goal
- Even if symptoms disappear, continue medication for 3-6 months
- Gradually reduce dosage once symptoms stop appearing, then completely discontinue treatment
- Sudden cessation of medication on one's own initiative often leads to recurrence
- Approximately half of chronic urticaria cases undergo spontaneous remission within 1 year
Management of Physical Urticaria
| Type | Triggering Factors | Measures |
|---|---|---|
| Dermographism (Skin Writing) | Friction from clothes, scratching | Wear loose-fitting clothing, control with medication |
| Cholinergic Urticaria | Sweating from exercise, bathing, stress | Take medication beforehand, avoid strenuous exercise |
| Cold Urticaria | Cold air, cold water | Keep warm, avoid sudden temperature changes |
| Solar Urticaria | Sunlight exposure | Use SPF 50+ sunscreen, shade |
| Heat Urticaria | Heat stimulation | Avoid hot baths, saunas |
| Delayed Pressure Urticaria | Prolonged pressure | Reduce time carrying heavy bags on shoulders |
Daily Life Precautions
Lifestyle Habits to Avoid Worsening
- Limit alcohol and spices (they worsen symptoms by dilating blood vessels)
- Avoid hot baths, take lukewarm showers
- Avoid tight underwear and restrictive clothing
- Do not rub skin vigorously
- Get enough sleep and manage stress
- Prevent infections (often worsens with colds and fatigue)
- During an attack, cooling the affected area can relieve itching
Dietary Considerations
- Unless specific allergens are confirmed, excessive dietary restrictions are unnecessary
- Rarely, some individuals may worsen with histamine-containing foods (old fish, fermented foods, red wine)
- Keep a food diary to identify your own worsening patterns
Features of Our Clinic's Urticaria Treatment
- Treats all types: acute, chronic, and physical
- View39 test and specific IgE test to identify allergens
- For chronic idiopathic cases, antihistamine dose escalation strategy (based on guidelines)
- For refractory cases, Omalizumab (Xolair) induction and maintenance is possible
- Blood tests for underlying conditions such as thyroid and H. pylori
- Emergency response for angioedema and anaphylaxis history
- Comprehensive management of underlying diseases with integrated internal medicine
- Walk-ins welcome, same-day appointments OK / Open daily 9 AM - 9 PM / 1 minute walk from Jujo Station
Don't Give Up Even if the Cause is Unknown
Most chronic urticaria cases are "idiopathic," but modern treatments can achieve symptom control in over 80-90% of patients. It is possible to control symptoms and aim for resolution, rather than thinking "it won't get better because the cause is unknown."
