Why does a bug bite still itch after a week, and what should I do about it?
Dec 01, 2025
Source: Cainiu Health
Dr. Liu Wenmin
Introduction
In general, if an insect bite remains itchy for a week, it may be due to residual insect saliva causing irritation, repeated scratching worsening the reaction, insect bite dermatitis, papular urticaria, eczema, or other causes. It is recommended to seek medical attention promptly, identify the underlying cause, and under a doctor's guidance improve symptoms through general measures, medication, or other treatments. In daily life, maintain a light diet and avoid spicy or irritating foods.
Generally, if an insect bite remains itchy for a week, it may be due to residual insect saliva causing irritation, repeated scratching worsening the reaction, insect bite dermatitis, papular urticaria, eczema, or other causes. It is recommended to seek medical attention promptly, identify the underlying cause, and then improve symptoms under a doctor's guidance through general care, medication, and other treatments. A detailed analysis is as follows:
1. Residual insect saliva irritation: When insects bite, they inject saliva containing foreign proteins into the skin, triggering a localized allergic reaction. Persistent itching can result from lingering saliva. Thoroughly rinse the affected area with running water or normal saline 2–3 times daily to remove residual saliva. After rinsing, gently pat dry with a clean towel, avoiding friction.
2. Worsened reaction due to repeated scratching: Scratching damages the skin barrier, increasing the release of inflammatory mediators, which intensifies itching and prolongs recovery time. Keep fingernails trimmed smooth and short. During itching episodes, apply a cool compress or gently pat the affected area. Non-irritating moisturizers can also be applied to relieve discomfort.
3. Insect bite dermatitis: An allergic inflammation caused by insect bites, characterized by redness and papules, with persistent itching. Follow a physician’s instructions to take oral antihistamines such as cetirizine hydrochloride tablets, loratadine capsules, or ebastine tablets. Additionally, apply calamine lotion topically to reduce the urge to scratch.
4. Papular urticaria: Often caused by bites from fleas or mites, this condition presents with spindle-shaped wheals and severe, prolonged itching. Use mometasone furoate cream topically and take oral antihistamines such as fexofenadine hydrochloride tablets, desloratadine dry suspension, or levocetirizine oral solution as directed. Also, thoroughly wash and sun-dry clothing and bedding to eliminate pathogens.
5. Eczema: Following an insect bite, damage to the skin barrier may lead to secondary eczema, presenting as red patches and blisters with recurrent itching. As prescribed, apply topical hydrocortisone butyrate cream and take oral medications such as diphenhydramine hydrochloride tablets, chlorpheniramine maleate tablets, or cyproheptadine hydrochloride tablets. Avoid contact with irritants such as soap and alcohol.
In daily life, maintain a light diet, avoid spicy and irritating foods, and consume more fresh fruits and vegetables rich in vitamins. Wear loose, breathable cotton clothing to minimize skin friction. Keep living areas dry and clean, regularly use insect repellents, and take preventive measures to reduce insect bites at the source.
