A 67-year-old woman developed severe edema of her right hand and forearm, for which she was treated with antibiotics, without benefit. The echography excluded a venous thrombosis. Subsequently, she referred a wasp sting before the development of the edema. Specific Hymenoptera venom immunoglobulin E (IgE) was found to be positive for paper wasp and yellow jacket. A large local reaction (LLR) was diagnosed due to the hymenoptera sting. Self-injectable epinephrine was prescribed for possible, though unlikely, systemic reactions following hymenoptera stings. LEARNING POINTS The differential diagnosis of an upper forearm and hand oedema may be challenging. In order to reach the correct diagnosis and to prescribe proper treatment, careful examination and history taking is essential. All possible causes should be taken into proper consideration. Large local reaction (LLR) is characterized by hot, flushed and thick edema after a hymenoptera sting. As the risk of a systemic reaction, upon the first sting following a consistent index LLR, it is important to recognize an LLR in order to prescribe self-injectable epinephrine to prevent the occurrence of anaphylaxis.