As an oncologist with extensive experience in treating patients undergoing chemotherapy, I can provide some insights into the duration of side effects, including how long one might feel bad after chemotherapy. The duration of feeling unwell after chemotherapy can vary significantly from person to person and depends on several factors, including the type of chemotherapy drugs used, the dosage, and the individual's overall health and response to the treatment. Acute nausea and vomiting are common immediate side effects that usually occur within a few minutes to hours after chemotherapy is administered. These symptoms often resolve within the first 24 hours. The peak of this acute reaction typically happens around 5 or 6 hours after the treatment. However, some patients may experience delayed nausea and vomiting, which starts more than 24 hours after chemotherapy and can last up to 5 to 7 days following the treatment. This can be particularly challenging and may require additional medication or interventions to manage. It's important to note that while these are general timeframes, each person's experience is unique. Some may have milder symptoms, while others may have a more severe or prolonged reaction. Medical professionals closely monitor patients and adjust treatment plans as necessary to manage side effects and improve the patient's quality of life. read more >>

Acute nausea and vomiting usually happens a few minutes to hours after chemo is given. It goes away within the first 24 hours. The worst of this acute vomiting most often happens about 5 or 6 hours after chemo. Delayed nausea and vomiting starts more than 24 hours after chemo and up to 5 to 7 days after treatment.read more >>