Redness from a wasp sting that is spreading

Wasp venom can cause pain, warmth, itch, and swelling around the sting. A large local reaction may extend beyond the original spot and peak later before easing. Infection is a separate possibility, particularly after scratching breaks the skin; [Cellulitis](/conditions/cellulitis/) causes infected skin that may become progressively warm, tender, swollen, and painful. Redness alone cannot tell these apart. Note when the sting occurred, whether the area is expanding, and whether symptoms are local or affecting the rest of your body. A wasp may not leave a stinger, but do not dig into the skin if you are unsure.

Move away from the insect, wash the area gently, and apply a cool compress wrapped in cloth. Avoid scratching and keep any broken skin covered. Follow a clinician's advice about antihistamines or other symptom relief, especially if you take regular medicines or have a medical condition. If infection is diagnosed, [Antibiotics For Skin Infection](/treatments/medical-dermatology/antibiotic-therapy-for-skin-infection/) may be prescribed; never use someone else's antibiotics.

Call emergency services immediately for difficulty breathing, wheezing, throat or tongue swelling, widespread hives, dizziness, faintness, or vomiting. Seek same-day medical advice if redness continues to expand with increasing pain, heat, pus, fever, or red streaks. A sting in the mouth, throat, or near the eye also needs urgent assessment.

Is this a large local reaction or cellulitis? Should I have an allergy action plan for future stings? Which symptoms mean I should use prescribed emergency medicine or seek immediate help?