Differential Diagnosis for Hives and Fever
- Single most likely diagnosis
- Urticaria (hives) due to a viral infection: This is a common cause of hives and fever, especially in children and young adults. Viral infections such as the common cold, influenza, or mononucleosis can trigger an allergic reaction, leading to hives and fever.
- Other Likely diagnoses
- Allergic reactions: Allergies to food, medications, or insect bites can cause hives and fever. Common culprits include penicillin, sulfa drugs, and foods like nuts, shellfish, or milk.
- Autoimmune disorders: Conditions like lupus or rheumatoid arthritis can cause hives and fever, although these are less common causes.
- Infections: Bacterial infections like strep throat or pneumonia can also cause hives and fever.
- Do Not Miss (ddxs that may not be likely, but would be deadly if missed)
- Anaphylaxis: A severe, life-threatening allergic reaction that requires immediate medical attention. Although rare, anaphylaxis can cause hives, fever, and other symptoms like difficulty breathing, rapid heartbeat, and a drop in blood pressure.
- Meningitis: A bacterial infection that causes inflammation of the membranes surrounding the brain and spinal cord. Meningitis can cause fever, hives, and other symptoms like headache, stiff neck, and confusion.
- Sepsis: A life-threatening condition that occurs when the body's response to an infection becomes uncontrolled and causes widespread inflammation. Sepsis can cause fever, hives, and other symptoms like confusion, shortness of breath, and abdominal pain.
- Rare diagnoses
- Serum sickness: A rare immune system reaction to certain medications or antiserum, which can cause hives, fever, and other symptoms like joint pain and swelling.
- Erythema multiforme: A rare skin condition that can cause hives, fever, and other symptoms like target-shaped lesions on the skin.
- Mastocytosis: A rare condition characterized by an accumulation of mast cells in the skin, which can cause hives, fever, and other symptoms like flushing and abdominal pain.