tPA for stroke is given as an intravenous infusion, typically over the course of about 60 minutes when using alteplase, the traditional formulation. A newer option, tenecteplase, is given as a single IV dose. Both must be started within a strict time window after symptoms begin, and the entire process, from brain scan to needle in the arm, is designed to move as fast as possible.
What tPA Does in the Body
An ischemic stroke happens when a blood clot blocks an artery supplying the brain. tPA (tissue plasminogen activator) is a clot-dissolving drug. It works by activating a natural protein in your blood called plasminogen, converting it into plasmin. Plasmin then breaks down fibrin, the mesh-like protein that holds a clot together. As the clot dissolves, blood flow to the affected part of the brain is restored.
The sooner this happens, the less brain tissue is permanently damaged. That’s why stroke teams treat tPA administration as a race against the clock.
The Time Window for Treatment
The standard eligibility window is within 4.5 hours of when symptoms started or were last known to be absent. The 2026 American Heart Association/American Stroke Association guideline recommends either alteplase or tenecteplase within this window to improve functional outcomes.
For some patients, that window can extend further. If advanced brain imaging shows there’s still salvageable tissue (areas not yet permanently damaged), IV thrombolysis may be reasonable up to 9 hours from when symptoms were last known to be absent, or up to 9 hours from the midpoint of sleep for people who wake up with stroke symptoms. This extended window isn’t available to everyone. It depends on what the imaging reveals about how much brain tissue can still be saved.
What Happens Before the Infusion
Before tPA can be given, the medical team needs to confirm two things: that you’re having an ischemic stroke (caused by a clot) and not a hemorrhagic stroke (caused by bleeding). A CT scan of the brain is required to rule out bleeding, and it takes less than five minutes. If there’s any sign of hemorrhage on imaging, tPA is off the table, because dissolving clots in someone who is already bleeding in the brain would be catastrophic.
Your blood pressure also has to be controlled before treatment can start. If your systolic pressure is above 185 or your diastolic is above 110, the team will work to bring it down first. Uncontrolled high blood pressure at those levels is an exclusion criterion because it increases the risk of bleeding complications once the clot-busting drug is in your system.
The stroke team will also check for other factors that could make tPA too dangerous: recent major surgery, a history of brain hemorrhage, active internal bleeding, very low platelet counts, or use of certain blood-thinning medications. These are absolute contraindications, meaning tPA won’t be given regardless of the stroke severity.
How the Drug Is Given
If you receive alteplase, the standard dose is 0.9 mg per kilogram of body weight. It’s split into two parts: a small initial portion is pushed through the IV line quickly as a bolus to get the drug working fast, and the remainder is infused slowly over the next 60 minutes. For a person weighing around 80 kg (about 175 pounds), the total dose would be roughly 72 mg.
Tenecteplase, the newer alternative, simplifies this considerably. It’s given as a single IV push at a dose of 0.25 mg/kg, with a maximum of 25 mg. There’s no hour-long drip. The 2026 AHA/ASA guideline now endorses tenecteplase alongside alteplase, noting its practical advantage: one dose, administered in seconds, rather than a 60-minute infusion. This is especially useful in emergency settings where patients may need to be transferred to another hospital or moved quickly to a procedure suite for additional treatment.
Monitoring After Treatment
The first 24 hours after receiving tPA are the most critical period. You’ll be in an intensive care or stroke unit where nurses perform continuous neurological assessments and blood pressure checks. They’re watching for any signs of deterioration, particularly symptoms that might indicate bleeding in the brain.
The medical team tracks your neurological status using a standardized scoring system. A significant worsening, defined as a 4-point or greater increase on the stroke severity scale within the first 24 hours, triggers immediate evaluation. This could signal a complication like intracranial hemorrhage, or it could mean the clot wasn’t fully dissolved or has reformed.
During this window, blood pressure is kept tightly controlled, and blood-thinning medications like aspirin or heparin are typically held to minimize bleeding risk. You’ll likely have a follow-up brain scan within 24 hours to check for any bleeding before those medications are restarted.
Bleeding Risk With tPA
The most serious complication of tPA is symptomatic intracranial hemorrhage, meaning bleeding in the brain severe enough to cause noticeable worsening. With alteplase, this occurs in about 3.6% of treated patients. Data on tenecteplase shows a lower rate of about 1.8%, which is one reason it has gained favor in recent guidelines.
That risk is real but has to be weighed against what happens without treatment. An untreated large vessel stroke can cause permanent disability or death. For patients who meet the eligibility criteria, the benefit of dissolving the clot and restoring blood flow generally outweighs the bleeding risk, which is why the screening process before administration is so thorough.
Alteplase vs. Tenecteplase
Both drugs work through the same basic mechanism, activating plasminogen to break down clots. The key differences are practical. Alteplase requires a 60-minute infusion with an IV pump and close monitoring throughout the drip. Tenecteplase is a single injection that takes seconds to administer. Both are effective at dissolving clots and improving outcomes when given within 4.5 hours.
Tenecteplase’s simplicity matters in real-world emergency care. If a patient arrives at a smaller hospital that doesn’t perform clot-retrieval procedures, a single-dose drug can be given quickly before transfer. It also reduces the chance of dosing errors and frees up nursing resources during a chaotic resuscitation. Many stroke centers have already shifted to tenecteplase as their first choice, and the latest AHA/ASA guideline supports either option equally.
Pediatric Stroke Treatment
Stroke in children is rare but does occur. The 2026 guideline offers the first formal guidance for pediatric patients, noting that alteplase may be considered for children aged 28 days to 18 years with a confirmed ischemic stroke presenting within 4.5 hours, if they have disabling deficits. The evidence suggests it’s safe in this age group, though its effectiveness is less certain than in adults. This represents a cautious step forward, as previously there was no standardized recommendation for clot-dissolving treatment in children.