Skip to main content
Drug Info

What happens if you take a double dose of blood thinner?

Taking a double dose of your blood thinner can be dangerous. Here’s what to do right away and how to protect your health.
SingleCare logo
By | Jun. 25, 2025 Medically reviewed by Karen Berger, Pharm.D.
Multiple pill bottles: What happens if you take a double dose of blood thinner?

Key takeaways

  • In some cases, taking a double dose of a blood thinner is relatively harmless. But in other cases, it can cause increased bleeding or other symptoms, requiring medical attention.

  • If you experience bleeding, headaches, nosebleeds, unexplained bruising, dizziness, blood in urine/stool, or vomiting blood after taking blood thinners, seek medical help.

  • Learn what to do if you miss a dose of your specific blood thinner medicine, so you’ll be prepared if it happens.

In this article:

Blood thinners can be life-saving medicines—and that’s no exaggeration. They significantly decrease the risk of blood clots, helping prevent heart attacks, strokes, pulmonary embolism, clogged blood vessels, deep vein thrombosis (DVT), and more. So for people prone to clotting, it’s vital to take them regularly and in the correct dosage. 

What happens, however, if you accidentally take more than directed? It’s uncommon, but certainly possible, and could have potentially serious effects. But don’t worry. Below, we’ve outlined what to do if you take a double dose of blood thinners, what to look out for, when to seek help, plus advice on how to avoid it in the first place. 

What are some common blood thinners?

More than eight million Americans take blood thinners, according to the National Blood Clot Alliance, so they’re a fairly common medication. Because they can help prevent so many serious conditions, doctors write millions of prescriptions for them every year. Some of the most popular ones include warfarin, Xarelto (rivaroxaban), Arixtra (fondaparinux), Eliquis (apixaban), Plavix (clopidogrel), heparin, and aspirin.

There are two different types of blood thinners: anticoagulants and antiplatelets. Anticoagulant medicines like warfarin or Xarelto reduce the formation of fibrin, a protein that assists in blood clotting. Antiplatelets like Plavix or aspirin, meanwhile, work by making blood platelets less likely to stick together. Both can be effective in preventing clots, but a healthcare professional will choose one or the other based on the patient’s specific condition, medical history, other drugs, and risk factors.  

What happens if you take a double dose of a blood thinner?

Whether you missed a dose and tried to make up for it, or accidentally took two pills instead of one, realizing you’ve taken a double dose can be startling. But it’s important not to panic. “In most cases, not much will happen if you mistakenly take a double dose,” says Dr. Karishma Patwa, MD, a cardiologist with Manhattan Cardiology and contributor to www.labfinder.com. Although, “you should monitor yourself for signs of bleeding or any change in symptoms, such as headaches.”

The most prevalent consequence is a higher risk of bleeding, including internal bleeding, which can be quite dangerous. Other symptoms may include:

  • Nosebleeds 
  • Blood in the urine/stool 
  • Bruising 
  • Dizziness 
  • Nausea, vomiting, and other gastrointestinal symptoms
  • Rash or dermatitis
  • Shortness of breath

The effects you experience, however, can depend on the specific medication. For example, “Taking an extra dose of aspirin won’t have that much effect on platelets, as the standard dose is already quite low,” says Dr. Austin Shuxiao, MD, founder and medical director of Peach IV. But “taking an extra dose of warfarin could have consequences as it may alter your international normalized ratio (INR) and clotting ability for days,” while a double dose of a P2Y12 inhibitor like Plavix can cause an “increased risk of bleeding from easy bruising, GI bleed, mucosal tissue, and joints, similar to double dosing other blood thinners.”

Side effects may also depend on the patient’s medical condition and health history. In fact, “Cardiologists will sometimes prescribe multiple blood thinners despite the risk of bleeding for specific clinical situations where the threat of clotting outweighs the risk of bleeding,” Dr. Shuxiao says. This includes people who have just received a new stent in the heart or who have recently had a major stroke.  

Always take your blood thinner exactly as prescribed. If you have a missed dose, don’t attempt to balance it out by doubling up on the next scheduled dose, as doing so could increase your risk of bleeding. When you start taking a blood thinner, ask your healthcare provider what to do in the event of a missed dose, as the instructions can vary depending on the medicine. If you are ever unsure, check with your pharmacist or healthcare provider.

When to seek medical attention

While taking a double dose of blood thinners isn’t always serious, it’s important to remember that it can be. In some extreme cases, it can even be fatal. So if you think you may have taken too much, be on the lookout for the symptoms listed above, and contact a healthcare provider if you experience them. 

“If you start to have bleeding, please seek medical attention as there are reversal agents for some blood thinners,” Dr. Patwa says. “If you are on Coumadin (warfarin), it is important to have your INR checked within a few days.” Checking your INR typically involves regular blood tests. 

If the symptoms are severe, especially bleeding, you may want to head straight to the emergency room to get immediate medical attention. Or, if you’ve taken a lot more than a double dose and fear an overdose, it might help to call poison control right away. 

How to avoid taking a double dose in the future

Avoiding double doses in the first place can save a lot of worry and potential consequences—and certain strategies can help you make sure you consistently take the correct dose at the correct time. 

“Many people who are on blood thinners are also on other medications, so it can be easy to mix up medications and take a double dose, so using a weekly pill case can certainly help prevent double dosing,” Dr. Patwa says.

“Patients can also make reminders on their phone to remind them at the exact time every day to take their medications and how much of each to take,” Dr. Shuxiao adds. “For older people who may be forgetful, it’s best to have aid or family members organize the medications ahead of time to prevent errors.”These tips might not completely eliminate the risk of taking a double dose, but as long as you follow your healthcare provider’s instructions, they should significantly reduce it.