How Long Does an Allergic Rash Last?
Hives, or urticaria, affect about 20 percent of all people at one time or another. They can start as a simple itch followed by swollen, red welts. The itching may be mild and annoying to severe and debilitating. Some things can make it worse: aggressive scratching, alcoholic beverages, exercise, and emotional stress.
Hives can happen once or linger and repeat. They can last minutes, hours, days, several weeks, months or even years. There are two types of hives: acute urticaria and chronic urticarial. The acute variety lasts for six weeks or less, while the chronic variety can stay or recur for more than six weeks.
Acute hives vs. chronic hives
The causes for each is very different. Acute hives are more common and usually caused by foods or food additives. Peanuts, eggs, nuts and shellfish are the most common allergen triggers. The hives will usually resolve themselves on their own, but treatment with an anti-itch cream can encourage healing.
Often, the cause of chronic hives is unknown. The immune system is usually the cause for about half of all cases. Occasionally an autoimmune disorder will cause the immune system to attack the skin, creating a chronic rash. Chronic hives may also be related to thyroid disease, hormonal problems and, very rarely, cancer.
Causes for hives
Plants. Contact dermatitis is common. Poison ivy is one type. These rashes can last two to three weeks.
Viruses, bacteria and fungi. Fungal infections caused by bacteria and fungi can cause hives as well as viral infections like herpes and bacterial infections like chicken pox. Ringworm can also cause hives and swollen skin. These types of rashes can last up to two weeks.
Foods and allergies. Pollen and dust mites are common allergens that cause skin rash. Chemicals can do the same. Rashes from food allergies can last several days.
Medications. Antibiotics can cause rash. In this case, alert your doctor so that another drug can be prescribed. It is important that this condition be addressed by a doctor as soon as possible. There could be unseen internal reactions as well. These types of rashes can last several weeks.
Sources: ACAAI, MedicineNet, MayoClinic