What causes the skin to become red, swollen, itchy, and hot?
Dec 01, 2025
Source: Cainiu Health
Dr. Liu Wenmin
Introduction
In general, redness, swelling, itching, and warmth of the skin may be caused by mosquito bites, contact with irritants, allergic dermatitis, acute eczema, erysipelas, or other conditions. Treatment methods such as general care or medication can be selected according to the specific situation. Daily skin cleansing should be maintained, and mild skincare products should be used. Protective measures should be taken when going outdoors to avoid insect bites and exposure to allergens.
Generally, skin that is red, swollen, itchy, and hot may be caused by mosquito bites, contact with irritants, allergic dermatitis, acute eczema, erysipelas, or other reasons. Depending on the specific situation, general treatments or medications can be used to improve symptoms. Detailed analysis is as follows:
1. Mosquito bites
When mosquitoes bite, they inject saliva containing foreign proteins that trigger a localized allergic reaction, causing blood vessel dilation and tissue fluid leakage, resulting in redness, swelling, itching, and warmth. Wash the affected area with soapy water and apply cold compresses to relieve discomfort. Avoid scratching to prevent infection.
2. Contact with irritants
Contact with irritants such as capsaicin or detergents can damage the skin barrier and provoke an inflammatory response. Immediately rinse off any residual irritant with clean water, change into clean clothing, and avoid further exposure to similar substances.
3. Allergic dermatitis
Exposure to allergens such as pollen or cosmetics activates the immune system, leading to the release of inflammatory mediators and causing redness, swelling, itching, and heat. Avoid known allergens and take medications such as loratadine capsules, cetirizine hydrochloride tablets, or ebastine tablets as directed by a physician.
4. Acute eczema
Skin inflammation triggered by genetic or environmental factors leads to epidermal cell damage, exudation, and symptoms including redness, swelling, itching, and heat. Keep the skin dry and follow medical advice for topical treatment with calamine lotion or desonide cream, along with oral antihistamines like fexofenadine hydrochloride tablets.
5. Erysipelas
An acute infection of the skin's lymphatic vessels caused by hemolytic streptococcus bacteria results in inflammation, manifesting as red, swollen, hot, and painful skin. Elevate the affected area to reduce swelling and take antibiotics such as penicillin V potassium tablets, cefuroxime axetil tablets, or azithromycin dispersible tablets as prescribed.
In daily life, maintain proper skin hygiene and use gentle skincare products. Take protective measures when going outdoors to avoid insect bites and allergen exposure. Eat a light diet and minimize consumption of spicy or irritating foods. If symptoms persist or worsen, or if fever develops, seek medical attention immediately.
