No-Pac : an tranexamic acid (TXA) reduce the need for nasal packing in adult patients presenting to the Emergency Department (ED) with spontaneous, serious, nosebleed? Nosebleed is a very common condition. In most cases nosebleeds stop with simple first aid measures, but some cases are more serious, leading to hospital admission or even death. Patients with serious nosebleed attending the ED are initially treated with vasoconstrictors (solution applied to the inside of the nostril) or cauterisation (briefly burning the blood vessel to seal it). If bleeding cannot be stopped with these measures, patients usually undergo nasal packing. Nasal packing involves stuffing the nasal passage tightly with a dressing to apply pressure to the source of the bleeding, an extremely uncomfortable and painful experience. The nasal pack is left in place for about 48 hours and patients are admitted to hospital for monitoring during this time. In other conditions where bleeding is a problem, TXA (injection and tablet) has been shown to help the normal blood clotting process, making clots less likely to break down. TXA has the potential to safely stop serious nosebleeds, and hence reduce the need for patients to undergo nasal packing and an in-patient hospital stay. This study is a double blind randomised controlled trial. Patients with a serious nosebleed that fails to stop after first aid and initial treatment in the ED are eligible to participate. In the ED, consented participants will receive either TXA or water (placebo) soaked into a small cotton wool roll and placed inside the bleeding nostril for a short time. After trial treatment, participants will resume the usual local care pathway. One week after the ED visit, the research nurse will telephone participants to collect information on any adverse reactions/complications relating to the study, and any further episodes of nosebleeds since the ED visit.