Alteplase: what it treats, how it is given, and side effects
Last updated September 7, 2026.
**Alteplase is a clot-dissolving medicine, a thrombolytic in the tissue plasminogen activator (tPA) class, given into a vein by a hospital team.** It converts plasminogen into plasmin, the enzyme that breaks apart the fibrin mesh holding a clot together, so blood can move again through a blocked artery or vein. Because it acts on clots throughout the body and not only the one causing the problem, bleeding is the main risk, which is why it is given only where your blood pressure, brain function, and puncture sites can be watched minute to minute. Timing drives the whole decision: the benefit in stroke and heart attack falls with every hour that passes after symptoms start.
What does it treat?
Alteplase is used for acute ischemic stroke, where a clot blocks an artery in the brain and causes sudden face droop, arm weakness, slurred or garbled speech, vision loss, or sudden severe imbalance. It is also used in acute ST-elevation heart attack, where crushing chest pressure, sweating, and arm or jaw pain come with specific changes on the ECG, and in acute massive pulmonary embolism, where a clot in the lung arteries causes sudden shortness of breath, low blood pressure, and strain on the right side of the heart. The brand name for these uses is Activase. A separate low-dose product, Cathflo Activase, is used only to reopen a central venous catheter that has clotted off, not to treat a clot in your body. Alteplase is not sold in combination with other drugs, and it is not the same as the blood thinners heparin, warfarin, or apixaban, which prevent new clots rather than dissolve an existing one. Related clot-dissolving drugs you may hear about include tenecteplase (TNKase) and reteplase (Retavase).
How do you take it?
Alteplase comes as a sterile powder in 50 mg and 100 mg vials that a pharmacist or nurse mixes with sterile water and runs through an IV pump; Cathflo Activase comes as a 2 mg vial. There is no tablet, no home dose, and no food rule, since nothing is taken by mouth. For acute ischemic stroke, the labeled adult dose is 0.9 mg/kg with a maximum of 90 mg total, with 10 percent given as a bolus over 1 minute and the rest infused over 60 minutes, started within 3 hours of when symptoms began. For heart attack, the accelerated regimen for people over 67 kg is a 15 mg bolus, then 50 mg over 30 minutes, then 35 mg over 60 minutes, for a total of 100 mg; people at or under 67 kg get weight-based amounts that reach the same 100 mg ceiling. For pulmonary embolism, the dose is 100 mg infused over 2 hours. For a blocked catheter, 2 mg is instilled into the line and may be repeated once after 120 minutes. Because the whole course is given in one sitting, there is no missed dose to make up. Tell the nurse right away if you get a sudden bad headache, feel any part of your body go weak or numb, notice your tongue or lip swelling, or see blood in your urine, stool, or vomit, since the infusion may be stopped on the spot.
Side effects to know
- Common: Bleeding or bruising around IV sites and blood draws is expected, and some people have bleeding gums or a nosebleed, nausea, fever, or a drop in blood pressure during the infusion.
- Serious: Bleeding into the brain is the most serious risk, and its signs are a sudden severe headache, new weakness or numbness, vomiting, confusion, seizure, or trouble staying awake. Also get help immediately for swelling of the tongue, lips, or throat (more likely if you take an ACE inhibitor such as lisinopril), heavy bleeding from any site, black or bloody stool, coughing up blood, a fast or irregular heartbeat, or purple discoloration of the toes with new kidney trouble.
Who should not take it?
Alteplase is not given if you have active internal bleeding, a bleeding disorder, bleeding in or around the brain now, recent brain or spinal surgery or serious head injury within the past 3 months, a known aneurysm, arteriovenous malformation, or certain brain tumors, or blood pressure that is severely high and not controlled. For heart attack and pulmonary embolism, a recent stroke also rules it out. Tell the team about every blood thinner and antiplatelet drug you take, including warfarin, apixaban, rivaroxaban, dabigatran, heparin, aspirin, and clopidogrel, since these add to bleeding risk, and about ACE inhibitors such as lisinopril or enalapril, which raise the risk of tongue and lip swelling. Recent major surgery, recent internal bleeding, a stomach ulcer, pregnancy, recent childbirth, diabetic eye bleeding, and a low platelet count all change the calculation and need to be mentioned even in an emergency. FDA labeling reports no adequate data in pregnancy or breastfeeding; the drug is used in pregnancy when the clot itself is life-threatening, and it is a large protein that is unlikely to pass into milk in a meaningful amount. There is no alcohol interaction with the infusion itself, but heavy drinking raises bleeding and fall risk during recovery, so tell your clinician what you actually drink.
When is it an emergency?
Call 911 for sudden face droop, arm weakness, slurred speech, a sudden severe headache, vomiting with confusion, a seizure, trouble breathing, swelling of the tongue or throat, chest pain, fainting, or bleeding you cannot stop with firm pressure. These are the drug-specific red flags after alteplase, and they are handled in an emergency department, not at home. Too much alteplase shows up as excessive bleeding rather than as typical overdose symptoms, and it is treated by stopping the infusion and giving blood products, so anyone who suspects a dosing error should call 911 or Poison Control at 1-800-222-1222. If someone collapses or stops breathing, start CPR and call 911 first.
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Common questions
What is the maximum dose of alteplase?
The ceiling depends on why it is given. For acute ischemic stroke, the dose is 0.9 mg/kg and the total never exceeds 90 mg, no matter how much you weigh. For heart attack and for pulmonary embolism, the total is 100 mg given over 90 minutes to 2 hours depending on the regimen. For clearing a blocked central catheter, the dose is 2 mg, which may be repeated once after 120 minutes. These are single-course doses given by a hospital team, so there is no daily total to track at home.
Can I drink alcohol after getting alteplase?
Alcohol does not interact with the infusion itself, and the drug clears from your blood within minutes. What matters is the days and weeks after, when your brain or heart is healing and you are usually on aspirin or another blood thinner. Alcohol raises bleeding risk, raises blood pressure, and raises fall risk, and a fall on a blood thinner is how many people end up back in the hospital. Ask your clinician for a specific limit based on your medicines and tell them your real intake, including binge weekends.
Is alteplase safe in pregnancy or while breastfeeding?
FDA labeling states there are no adequate and well-controlled studies in pregnant people, so there is no clean safety answer from trials. In practice, alteplase is used during pregnancy when a clot is threatening the life of the pregnant person, because an untreated massive pulmonary embolism or major stroke is more dangerous than the drug. Bleeding around the placenta and at delivery is the specific added concern, so the obstetric team is involved in the decision. For breastfeeding, there is no data, but alteplase is a large protein with a half-life of about 5 minutes, so meaningful transfer into milk is not expected.
Do I need to avoid food or fast before alteplase?
There is no food interaction, since alteplase goes into a vein and never passes through your stomach. In a stroke, the team will usually keep you from eating or drinking until a swallow screen is done, because a stroke can weaken swallowing and send food into the lungs. Before a heart procedure you may also be kept nothing by mouth. Follow what the team tells you rather than eating or drinking on your own, and ask before taking any pill you brought from home.
What are the signs of getting too much alteplase?
Too much alteplase shows up as bleeding rather than as sedation or a rash. Watch for a sudden severe headache, new weakness or numbness, confusion, vomiting, trouble staying awake, blood in urine, black or bloody stool, coughing up blood, or bleeding from an IV site that soaks through gauze. There is no reversal drug you take at home; treatment is stopping the infusion and giving blood products such as cryoprecipitate. Call 911 for any of these signs, and call Poison Control at 1-800-222-1222 if a dosing error is suspected.
Which medicines interact with alteplase?
Anything that thins blood adds to the bleeding risk: warfarin, apixaban, rivaroxaban, dabigatran, heparin and low molecular weight heparins, aspirin, clopidogrel, ticagrelor, and glycoprotein IIb/IIIa inhibitors. Recent doses of these often change whether alteplase can be given at all, so the exact time of your last dose matters. ACE inhibitors such as lisinopril, enalapril, and ramipril raise the risk of tongue and lip swelling during the infusion. Bring your medicine list or bottles with you, because in an emergency this history is the fastest thing to get wrong.