How can I differentiate between a mild allergic reaction and anaphylaxis in a patient who has been stung by a bee?

To differentiate between a mild allergic reaction and anaphylaxis in a patient stung by a bee, assess the severity and systems involved:

• Mild allergic reaction typically involves localized symptoms such as erythema, pruritus, swelling, or a large local reaction (oedema and erythema >10 cm) that peaks 24–48 hours after the sting without systemic involvement.
• Anaphylaxis is a severe, life-threatening systemic hypersensitivity reaction characterized by rapidly developing problems involving the airway (e.g., pharyngeal or laryngeal oedema), breathing (e.g., bronchospasm with tachypnoea), and/or circulation (e.g., hypotension and/or tachycardia), often accompanied by skin and mucosal changes such as urticaria or angioedema.
• Signs of anaphylaxis include difficulty breathing, swelling of the mouth, throat or tongue, hypotension, tachycardia, and collapse or shock.
• In contrast, mild reactions do not involve airway compromise, respiratory distress, or cardiovascular instability.
• Any suspicion of systemic hypersensitivity or anaphylaxis requires immediate emergency treatment and urgent hospital admission.

Therefore, the key differentiators are the presence of systemic symptoms affecting airway, breathing, or circulation in anaphylaxis versus localized skin symptoms in mild allergic reactions NICE CKS,NICE CKS,NICE CG134.