- Related to meds, cold weather, allergies to food, infxn, hereditary, idiopathic
- Erythematous eruption w/raised wheals, very itchy, vary in size, any location
- Acute resolves w/in 24h, can be acute or chronic
- Can be assoc w/angioedmea and/or anaphylaxis if severe
- Multiple, variably shaped, well circumscribed, edematous areas, sometimes surrounded by erythematous rings