Allergic reactions can affect the skin, producing two main types of rashes: urticaria (also known as hives, nettle rash, or welts) and eczema (see atopic dermatitis).
Urticaria
Urticaria presents as a red, itchy, bumpy rash that is often short-lived. It can appear in various shapes and sizes and may affect any part of the body. It is a very common condition, affecting approximately 1 in 5 people at some point in their lives.
In some individuals, urticaria is accompanied by angioedema—a deeper swelling that often affects the lips, eyelids, tongue, or hands. These swellings can appear dramatic but are usually benign.
Often, no specific cause is identified for urticaria or angioedema. However, they may occur as part of an allergic reaction to foods, medications or insect stings.
Additionally, physical or environmental triggers can provoke urticaria, including:
Angioedema without Urticaria
Angioedema can occur on its own, without accompanying urticaria. A notable cause of this is the use of ACE inhibitors, a class of blood pressure-lowering medications. Common examples in this group include Lisinopril, enalapril and ramipril.
Interestingly, such reactions may develop after months or even years of regular treatment, making this association easy to overlook.
Treatment
Urticaria is primarily caused by the release of histamine in the skin. Therefore, antihistamines are the cornerstone of treatment. The preferred options are non-sedating antihistamines, such as:
In some cases, the rash persists for weeks or months which could suggest chronic urticaria. Chronic urticaria may require specialist assessment and management to ensure appropriate and effective treatment