Which of the following statements about thrombolytic therapy timing is most accurate?

• A. Within the first hour
• B. Within 4-6 hours after onset
• C. Best outcomes occur between 2 and 4 hours after onset
• D. There is no time limit for therapy

Answer: (C)

Thrombolytic therapy is highly time-dependent because brain tissue is at risk of irreversible damage as time passes. The goal is to restore blood flow while keeping the risk of bleeding as low as possible. The window around 2 to 4 hours after onset represents the period where salvageable tissue (the penumbra) can be most effectively saved with a favorable balance of benefit to risk.

Giving treatment within this 2–4 hour window maximizes the chances of meaningful neurological recovery. Getting therapy very early is beneficial, but the phrase that “best outcomes occur” specifically in the 2–4 hour range reflects this balance point most consistently across patients. Waiting longer than about 4 hours tends to reduce benefit and increase risk, while saying there’s no time limit is inaccurate.