After a subarachnoid haemorrhage, complications are common and increase the overall rate of disability and death from the condition. Despite some advances in preventing, detecting and treating these complications, the rates of complications and associated risks remain high. Further research into ways to reduce complications of subarachnoid haemorrhage. Transcutaneous vagus nerve stimulation (tVNS) is a technique where a small handheld device is attached to an earpiece which stimulates the nerves to the ear. This is given for short periods and may help improve blood flow and reduce inflammation in the brain. The intervention has been safely used and licensed in seizures, headache and severe depression. This study will look to see if it is feasible and tolerable to have tVNS twice daily for 5 days after subarachnoid haemorrhage, and whether it can help reduce the risk of complications from subarachnoid haemorrhage. The participant will be randomly allocated to receive either tVNS or a dummy intervention, known as sham. The researchers will collect some personal and clinical details such as diagnosis, medications, age, blood test results, as well as some details about the subarachnoid haemorrhage. The researchers will also complete brief questionnaires with the participant to assess symptoms. They will take measurements of heart rate, pupil response, and brain activity using a cap. The participant will then be randomly allocated to either receive the tVNS or sham intervention. Next, the research team will apply the earpiece to their ear twice a day for 45 minutes, for a total of 5 days. At the end of the 5-day study period, the intervention will be complete. The researchers will arrange a follow-up meeting on discharge and at 6 weeks, to assess the participants symptoms and recovery. Previous studies have shown that tVNS is safe and well tolerated, including a recent review of tVNS studies which evaluated the side effects experienced by 1322 patients receiving tVNS. The main side effects include localised tingling/numbness/pain/redness around the ear (17%), headaches (3%), dizziness (1%), facial droop (1%), nausea (1%), nasal discharge (2%). Rarely, palpitations or a slow heart rate may occur. They will continue to receive full medical treatment and observation alongside the study. They are free to withdraw from this study if they find it too demanding on top of their other activities.