Also called: Anti-platelet drugs · Anticoagulants
Important: This page is general information, not medical advice. It does not recommend or prescribe any treatment. Always consult your doctor or pharmacist before starting, stopping or changing any medicine.
About Blood Thinners
Blood thinners are medicines that prevent blood clots from forming. They do not break up clots that you already have. But they can stop those clots from getting bigger. It's important to treat blood clots, because clots in your blood vessels and heart can cause heart attacks, strokes, and blockages.
You may need a blood thinner if you have:
- Certain heart or blood vessel diseases
- An abnormal heart rhythm called atrial fibrillation
- A heart valve replacement
- A risk of blood clots after surgery
- Congenital heart defects
There are different types of blood thinners:
- Anticoagulants, such as heparin or warfarin (also called Coumadin), slow down your body's process of making clots.
- Antiplatelets, such as aspirin and clopidogrel, prevent blood cells called platelets from clumping together to form a clot. Antiplatelets are mainly taken by people who have had a heart attack or stroke.
When you take a blood thinner, follow the directions carefully. Blood thinners may interact with certain foods, medicines, vitamins, and alcohol. Make sure that your health care provider knows all of the medicines and supplements you are using.
You may need regular blood tests to check how well your blood is clotting. It is important to make sure that you're taking enough medicine to prevent clots, but not so much that it causes bleeding.
Bleeding is the most common side effect of blood thinners. They can also cause an upset stomach, nausea, and diarrhea.
Other possible side effects can depend on which type of blood thinner that you are taking.
Call your provider if you have any sign of serious bleeding, such as:
- Menstrual bleeding that is much heavier than normal
- Red or brown urine
- Bowel movements that are red or black
- Bleeding from the gums or nose that does not stop quickly
- Vomit that is brown or bright red
- Coughing up something red
- Severe pain, such as a headache or stomachache
- Unusual bruising
- A cut that does not stop bleeding
- A serious fall or bump on the head
- Dizziness or weakness
It sits within Blood, Heart and Circulation and Drug Therapy.
When to speak to someone. Reading about a topic cannot tell you whether it applies to you. Speak to a doctor or pharmacist if symptoms are severe, sudden, getting worse, or simply not going away — and seek emergency care immediately for chest pain, breathing difficulty, sudden weakness or confusion, or a serious allergic reaction.
Research on Blood Thinners
940 studies areregistered for this condition on ClinicalTrials.gov, the U.S. National Library of Medicine's public registry. A selection is below — the links go straight to the registry entry, not to a summary of ours.
What a registered study does and does not mean. Registration means a study exists and has been declared publicly. It says nothing about whether the treatment being tested works, is safe, or is available to you. Many studies find no benefit — that is what research is for. Never seek out an experimental treatment on the strength of a registry entry alone.
Research currently under way
- DOAC in Chinese Patients With Atrial FibrillationChinese University of Hong Kong
- Zastaprazan for the prEvention of Upper GI Bleeding in Ischemic StrokeAsan Medical Center
- Extended Prophylactic Anticoagulation Following Spinal Surgery for Metastatic DiseaseJames Bayley
- Risk Score of Embolism in Patients With AF Undergoing DOAC TherapyHospital Universitari Vall d'Hebron Research Institute
- Prospective Study of Antiplatelet and Anticoagulation Therapy in Hereditary Haemorrhagic TelangiectasiaUniversity Hospital, Clermont-Ferrand
- Shared Decision for Drug Interactions in Oral AnticoagulationUniversity of Utah
Research already completed
- The Effect of Pecha-Kucha Method Training on the Knowledge and Skills of Nurses Regarding Anticoagulant Drug AdministrationIstanbul Saglik Bilimleri University
- Apixaban vs Rivaroxaban vs No Anticoagulant to Prevent EHIT After Great Saphenous Vein Laser AblationHeart, Artery, and Vein Center of Fresno
- The Impact of Factor Xa Inhibition on Thrombosis, Platelet Activation, and Endothelial Function in Peripheral Artery DiseaseVanderbilt University Medical Center
- Replication of the EINSTEIN-DVT Anticoagulant Trial in Healthcare Claims DataBrigham and Women's Hospital
- Replication of the RECORD1 Anticoagulant Trial in Healthcare Claims DataBrigham and Women's Hospital
- The Efficacy and Safety of Non-vItamiN K antaGonist oraL Anticoagulants for intermEdiate Stroke Risk in Patients With Atrial Fibrillation (SINGLE-AF)Yonsei University
Study data from ClinicalTrials.gov, a service of the U.S. National Library of Medicine. Retrieved 2026-07-30. Registry entries are supplied by study sponsors and investigators; ClinicalTrials.gov does not verify their scientific validity. PocketsInfo is not affiliated with, and not endorsed by, the NLM or the NIH.
Where to read more
Rather than paraphrase, we point you to the primary sources. Every link below is to a government health agency, a national institute or a recognised medical body — grouped by what you are trying to find out.
Start Here
- AnticoagulantsTexas Heart Institute
- Anticoagulants and Drug-Food InteractionsNational Jewish Health
- Blood Thinner Pills: Your Guide to Using Them SafelyAgency for Healthcare Research and Quality
- What Are Anticoagulants and Antiplatelet Agents?American Heart Association
Diagnosis and Tests
- Pharmacogenetic TestsNational Library of Medicine
- Therapeutic Drug MonitoringNational Library of Medicine
Related Issues
- Blood Thinners and Dental CareAmerican Academy of Oral Medicine
- Blood Thinners: Can I Still Get Blood Clots?Mayo Foundation for Medical Education and Research
- Medication Interactions: Food, Supplements, and Other DrugsAmerican Heart Association
- Prothrombin Time Test and INR (PT/INR)National Library of Medicine
- Warfarin Side Effects: Watch for InteractionsMayo Foundation for Medical Education and Research
Genetics
- Clopidogrel resistance: MedlinePlus GeneticsNational Library of Medicine
- Warfarin sensitivity: MedlinePlus GeneticsNational Library of Medicine
Clinical Trials
- ClinicalTrials.gov: AnticoagulantsNational Institutes of Health
- ClinicalTrials.gov: HeparinNational Institutes of Health
- ClinicalTrials.gov: Platelet Aggregation InhibitorsNational Institutes of Health
- ClinicalTrials.gov: WarfarinNational Institutes of Health
Medical subject headings
Clinicians and researchers index this subject under Heparin, Warfarin, Platelet Aggregation Inhibitors, Anticoagulants. These are the terms to use when searching medical literature.
This page is built from the MedlinePlus health topic record for Blood Thinners, a service of the U.S. National Library of Medicine (NLM), National Institutes of Health. Information is from MedlinePlus.gov. PocketsInfo is not affiliated with, and is not endorsed by, the NLM or the NIH. Retrieved 30 July 2026.