Biphasic or rebound anaphylaxis is a recurrence of anaphylaxis after appropriate treatment, which can happen without any additional exposure to the allergen. The recurrence rate is up to 20% . The second attack can occur anywhere from 1 hour to 72 hours after the initial attack, commonly within 10 hours. Due to the risk of biphasic anaphylaxis, it is crucial to seek immediate medical attention and stay in the hospital after the initial attack to monitor the condition. The symptoms of biphasic anaphylaxis are the same as anaphylaxis, but they may differ in severity. Symptoms of this second phase of anaphylaxis are typically mild or moderate, but there is no guarantee that the second event won’t become a life-threatening one. The symptoms can rebound, returning hours or even days after receiving an epinephrine injection. The risk of a rebound anaphylactic reaction makes proper medical evaluation and aftercare crucial, even for people who feel fine after treatment with epinephrine.