A stroke is a part of the brain losing its blood supply: usually because an artery is blocked by a clot (about 85%), sometimes because one has burst (about 15%). Brain tissue dies within minutes of losing its supply and does not grow back, so everything about stroke treatment is organised around time. The treatments are good, some of them remarkably so, and almost all of them stop working a few hours after the stroke starts.
1. Recognising it
FAST — Face drooping, Arm weakness, Speech difficulty, Time to call 999 — catches most strokes in the front of the brain. It is close to blind to the roughly one in five in the back of the brain, which present as sudden vertigo, unsteadiness, double vision, difficulty swallowing or a violent headache, and get called labyrinthitis, migraine or drink. Anyone with sudden vertigo who cannot walk unaided is having a stroke until proved otherwise. A quarter of strokes are in people under 65. The recognising-it chapter covers the missed ones, TIA, and stroke in children.
2. The clock
For a blocked artery there are two treatments. Thrombolysis, a clot-dissolving injection, works up to 4.5 hours from the last time the person was well, and works far better in the first ninety minutes than in the last ninety. Thrombectomy, pulling the clot out through a catheter, is for the larger blockages and works up to 6 hours in everyone eligible and up to 24 hours in people whose scans show brain still worth saving; it is the most effective treatment in stroke medicine, with roughly one extra person independent for every three treated. For a bleed, the treatment is to stop it growing: blood pressure down to a target within an hour, and any blood-thinning drug reversed within the hour.
Every window, with the benefit and the harm in absolute numbers and a decision sequence for "which one, if any", is in the clock chapter. The printable timeline has it on one sheet.
3. What should happen in hospital
A scan within the hour
Immediately, if any of the treatments above might apply. It says bleed or blockage, and with a dye injection it shows where the blockage is.
The reperfusion decision, in minutes not hours
The UK average from door to clot-busting drug was 56 minutes in 2024–25. The best units do it in under half an hour.
A swallow check within four hours
Before anything is given by mouth. Aspiration pneumonia is one of the commonest avoidable causes of death after a stroke.
Aspirin within 24 hours
Once a bleed is excluded. After a minor stroke or TIA, two antiplatelets for three to four weeks then one.
A stroke unit, not a general ward
Stroke unit care on its own reduces death and dependency, independently of any drug.
Blood pressure left alone, mostly
In the first day it is only lowered if it is very high or a treatment requires it. After thrombectomy, forcing it below 140 does harm; that is new in 2026.
Rehabilitation that starts within a day or two
The UK guideline asks for three hours a day, five days a week, for anyone who can take part.
The hospital checklist chapter has each of these with its time limit and the reason.
4. After the first days
Two jobs, and they are the ones most often left half-done. Finding the cause: a narrowed neck artery that needs an operation within a fortnight, an irregular heart rhythm that a single ECG misses and a longer monitor finds, a hole in the heart in a younger person, or a rarer cause that needs a specific test. Preventing the next one: the right blood thinner for the cause, cholesterol below a target most people have never heard, blood pressure below 130, and the changes to daily life that move the risk. Finding the cause and preventing the next one each have a chapter, with the time limits and the targets.
5. Where UK and US guidance differ
The American Heart Association published a full new acute stroke guideline in January 2026; the UK's National Clinical Guideline for Stroke dates from 2023 and NICE's guideline was amended in 2025. They agree on almost everything that matters at the bedside. Where they differ: the US allows clot-busting up to 24 hours for a large blockage when thrombectomy is unavailable and the UK does not; the UK sets a firmer blood-pressure rule for bleeds; the US uses a reversal drug for the newer blood thinners that the UK reserves for trials; and the US endorses ambulances with CT scanners on board. The bigger gap is not guidance but delivery: thrombectomy in England reaches a fraction of the people estimated to be eligible for it. Each chapter ends with the differences that apply to it.