Hives, also known as urticaria, are a common skin condition that can cause concern, especially when accompanied by other symptoms like fever. Many wonder if hives directly cause a fever or if their simultaneous appearance signals an underlying issue. This article clarifies the relationship between hives and fever, explaining when they might occur together and what it could mean for your health.
What Are Hives?
Hives are characterized by the sudden appearance of raised, itchy welts on the skin. These welts can vary in size, from small spots to large patches, and may be reddish or skin-colored, often blanching when pressed. They can appear on any part of the body and are transient, meaning they can change shape, move around, disappear, and reappear over short periods, typically lasting less than 24 hours in a single spot.
Hives develop when the body releases histamine and other chemicals, often in response to various triggers. Common causes include allergic reactions to foods, medications, or insect stings. Physical stimuli like pressure, cold, heat, exercise, or stress can also induce hives.
What Is Fever?
A fever indicates an elevation in the body’s temperature above its normal range, typically around 98.6°F (37°C). Most medical professionals consider an oral temperature of 100.4°F (38°C) or higher to be a fever. This rise in temperature is often a natural immune response to combat infection or inflammation.
Fevers serve as a defense mechanism, creating an environment less favorable for pathogens to thrive. While a fever can cause discomfort, such as chills, sweating, and muscle aches, it is usually a temporary symptom.
When Hives and Fever Co-Occur
Hives themselves typically do not generate a fever; their concurrent appearance often points to an underlying condition. When both hives and a fever are present, it suggests a systemic response to an internal trigger, indicating various health issues from common infections to complex immune disorders.
Infections are a frequent cause for both hives and fever. Viral infections, such as the common cold, influenza, mononucleosis, or COVID-19, can trigger an immune response manifesting as a rash and elevated body temperature. Bacterial infections like strep throat or urinary tract infections may also lead to this combination of symptoms.
Systemic allergic reactions, particularly to medications or foods, can also result in both hives and a fever. Certain drugs, including antibiotics like penicillin or nonsteroidal anti-inflammatory drugs (NSAIDs), are known to cause such reactions, where the immune system overreacts, releasing chemicals that cause skin manifestations and sometimes a fever.
Autoimmune conditions, where the immune system mistakenly attacks healthy body tissues, can present with both skin symptoms and systemic inflammation. Diseases like lupus or vasculitis may involve the immune system attacking blood vessels or other tissues, leading to itchy, lumpy rashes (hives) and a persistent fever as part of the body’s generalized inflammatory state. The fever in these scenarios is a consequence of the body’s internal battle, not a direct result of the skin rash itself.
When to Seek Medical Care
While many cases of hives are mild and resolve on their own, a fever alongside hives can signal a need for medical attention. This is particularly important if symptoms suggest anaphylaxis, a severe allergic reaction. Signs of anaphylaxis include difficulty breathing, wheezing, swelling of the face, lips, or throat, dizziness, or a sudden drop in blood pressure. This situation requires immediate emergency medical care.
Medical consultation is advisable if the fever is high (e.g., 103°F or 39.4°C or higher in adults) or persists for more than a few days. If hives are widespread, painful, blistering, or rapidly worsening, a healthcare provider should evaluate them. Professional guidance is also important if the cause of the hives and fever is unknown, or if the affected individual is an infant or has underlying health conditions.