What causes red, itchy bumps appearing below the waist?

Red bumps accompanied by itching below the waist may involve various skin diseases or pathological conditions. Common causes include, but are not limited to:

1. Allergy: Contact with allergens such as pollen or willow fluff, or ingestion of certain foods like crabs or shrimp may trigger allergic reactions, leading to red bumps and itching on the skin.

2. Urticaria (hives): A common skin condition characterized by the sudden appearance of red or skin-colored welts, often related to food, medication allergies, or environmental factors.

3. Eczema: Associated with immune, genetic, psychological, and other factors, it typically presents as small red bumps or丘疱疹 (papulovesicles), accompanied by itching.

4. Fungal infection: Such as jock itch (tinea cruris), commonly occurring in warm and humid environments, especially in the area below the waist.

5. Insect bites: In summer or areas with many insects, insect bites may trigger allergic reactions, causing red swellings and itching on the waist area.

6. Herpes zoster: Caused by the varicella-zoster virus infection, it presents with symptoms such as blisters, pain, or swelling.

For the above situations, patients are advised to avoid scratching to prevent worsening symptoms or secondary infections; maintain clean and dry skin; wear loose and breathable clothing; and seek timely medical attention for detailed examination by a qualified physician to confirm diagnosis and receive appropriate treatment.