You should be concerned about a wasp sting if you experience any signs of a severe allergic reaction or if the sting leads to infection or other serious symptoms. Immediate emergency care (call 911) is needed if you have trouble breathing, wheezing, difficulty swallowing, hoarseness, chest tightness, speech difficulties, fainting, or confusion soon after the sting. Also, stings in sensitive areas like inside the mouth, throat, or eye require urgent medical attention. You should seek medical care promptly if you develop widespread hives or swelling, stomach pain, vomiting, or fever. Watch for increased redness, swelling larger than 4 inches, redness spreading after 3 days, or signs of infection (pus, warmth) which may require antibiotics. If you get multiple stings (more than 5 per 10 pounds of body weight), seek care. Persistent pain and swelling lasting more than a day or large local reactions may also need evaluation by a healthcare provider. Those with prior severe allergic reactions to stings should carry epinephrine and seek immediate care if stung again. Signs of life-threatening allergic reaction (anaphylaxis) include tightness in the throat or chest, coughing, wheezing, nausea, vomiting, dizziness, fainting, profuse sweating, anxiety, and extensive hives. Such symptoms require immediate emergency intervention. In most people, wasp stings cause only mild reactions like pain, redness, swelling, and itching at the sting site, which usually improve within hours to a couple of days. Home treatment and observation for worsening symptoms or allergic reactions are important.

When to be concerned about a wasp sting:

• Immediate emergency (call 911): breathing difficulty, wheezing, throat swelling, confusion, fainting, sting in mouth/throat/eye
• Urgent care: widespread hives, large swelling, stomach pain, vomiting, multiple stings
• Medical evaluation: redness getting larger after 3 days, signs of infection, persistent severe pain/swelling, previous severe allergic reaction
• Severe allergic reaction signs (anaphylaxis): chest tightness, cough, nausea, dizziness, extensive hives, unconsciousness

Common mild symptoms:

• Localized pain, swelling, redness, itching, and heat at sting site
• Usually improve in 1-2 days without complications

Prevention and preparedness:

• Avoid provoking wasps and know your allergy status
• Carry epinephrine if allergic
• Seek prompt care if severe reaction develops

These guidelines help distinguish when a wasp sting is a mild nuisance and when it demands urgent or emergency medical attention.