Refer to secondary care for patients with persistent nausea and vomiting if there are red flag features suggesting serious underlying conditions, such as suspicion of cancer, gastrointestinal obstruction, or other acute surgical conditions NICE CKS,NICE NG12.
Specifically, in adults aged 55 and over, consider urgent referral if nausea and vomiting are associated with weight loss, raised platelet count, or other alarm features NICE CKS,NICE NG12.
In children and young people, refer to specialist care if there are red flag symptoms such as bile-stained vomit, haematemesis, persistent or projectile vomiting, or signs of distress, faltering growth, or complications NICE NG1,NICE CKS.
Additionally, consider referral if nausea and vomiting are treatment-resistant or if there is suspicion of serious conditions like intracranial pressure, bowel obstruction, or malignancy based on clinical assessment NICE CKS,NICE NG1.