Worst Pills, Best Pills

An expert, independent second opinion on more than 1,800 prescription drugs, over-the-counter medications, and supplements

Blood-clotting Inhibitors


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DRUG AND DIETARY SUPPLEMENT PROFILES

A comprehensive review of the safety and effectiveness of this drug. If the drug is not a Do Not Use product, information on adverse effects, drug interactions and how to use the medication are included.

ticlopidine (TICLID)
  • We list this drug as a Do Not Use drug because it is only somewhat more effective than aspirin, but causes bone marrow toxicity and high blood cholesterol levels.

WORST PILLS, BEST PILLS NEWSLETTER ARTICLES
Drug Interactions for the Antidepressant Drug Desipramine (NORPRAMIN)
September 2023
Patients taking the oral antidepressant drug desipramine (Norpramin) should be aware that it has clinically important interactions with many other prescription medications. Public Citizen’s Health Research Group has designated desipramine, a tricyclic antidepressant, as a Limited Use drug; antidepressants in other drug classes are safer and better tolerated.
Important Drug Interactions for the Stomach-Acid–Suppressing Drug Cimetidine
August 2023
Patients taking the stomach-acid–suppressing drug cimetidine, which is available over the counter as a generic, should be aware of its clinically important interactions with many other prescription medications.
Important Drug Interactions for the Stomach-Acid–Suppressing Drug Rabeprazole (ACIPHEX)
June 2023
Patients taking the stomach-acid-suppressing drug rabeprazole (ACIPHEX) should be aware that it has clinically important interactions with many other prescription medications. Public Citizen’s Health Research Group has designated rabeprazole, a protein pump inhibitor, as Limited Use.
Important Drug Interactions for the Antifungal Drug Voriconazole
May 2023
Patients taking the antifungal drug voriconazole (VFEND), which is marketed in both oral and injectable forms, should be aware that it has clinically important interactions with many other prescription medications.
Important Drug Interactions for the Hypertension Drug Felodipine
April 2023
Patients taking the commonly prescribed calcium channel blocker felodipine should be aware that it has clinically important interactions with many other prescription medications as well as the dietary supplement St. John’s wort.
Drug and Food Interactions for the Thyroid Medication Levothyroxine
March 2023
Patients taking the widely prescribed hypothyroidism drug levothyroxine should be aware that it has clinically important interactions with many other prescription and over-the-counter medications, dietary supplements and even certain foods.
Important Drug Interactions for the SSRI Medication Fluvoxamine
December 2022
Patients taking fluvoxamine (LUVOX), a selective serotonin reuptake inhibitor (SSRI), should be aware that it has clinically important interactions with many other prescription and over-the-counter medications.
Important Drug Interactions for the Antidepressant Citalopram (CELEXA)
October 2022
Patients taking the commonly prescribed antidepressant citalopram should be aware that it has clinically important and potentially dangerous interactions with many other prescription and over-the-counter medications.
Important Drug Interactions for the Combination Antiviral COVID-19 Drug PAXLOVID
August 2022
Patients taking the oral combination antiviral drug PAXLOVID (nirmatrelvir and ritonavir), which is used to treat COVID-19, should be aware that it has clinically important and potentially dangerous interactions with many other prescription medications.
Drug-Induced Gallstones (Cholelithiasis)
June 2022
Learn about several drugs that can promote the formation of gallstones — stones in the gallbladder (a condition known as cholelithiasis) — and what you can do about it.
Important Drug Interactions for NSAIDs
May 2022
Patients taking any of the widely used nonsteroidal anti-inflammatory drugs (NSAIDs) should be aware that they all have clinically important interactions with many other medications.
Important Drug Interactions for the Antidepressant Fluoxetine (PROZAC, SYMBYAX)
February 2022
Patients taking the commonly prescribed antidepressant fluoxetine should be aware that it has clinically important and potentially dangerous interactions with many other prescription and over-the-counter medications.
Why You Should Avoid the Herbal Supplement St. John’s Wort
December 2021
Learn why we have designated St. John’s wort, an herbal dietary supplement that is commonly available in capsules, tablets or teas, as Do Not Use.
Important Drug Interactions for the Antifungal Drug Itraconazole
November 2021
Patients taking the oral antifungal drug itraconazole (SPORANOX, TOLSURA) should be aware that it has clinically important interactions with many other prescription medications that can affect the safety or effectiveness of itraconazole or the interacting drugs.
Important Drug Interactions for the Stomach-Acid–Suppressing Drugs Lansoprazole and Dexlansoprazole
October 2021
Patients taking the commonly used stomach-acid–suppressing drugs lansoprazole (PREVACID, PREVACID 24 HR) and dexlansoprazole (DEXILANT) should be aware that these drugs have clinically important interactions with many other prescription medications.
Medications That Cause Gastrointestinal Bleeding
September 2021
Gastrointestinal bleeding is a common cause of hospitalization and in severe cases can result in death. Find out which commonly used medications can cause gastrointestinal bleeding.
Direct-to-Consumer Advertising May Be Driving Up Medicare Drug Spending
September 2021
A recent Government Account¬ability Office report found that direct-to-consumer prescription-drug advertising may be a major factor contributing to rising spending on medications by the Medicare program and its beneficiaries.
Important Drug Interactions for the Hypertension and Angina Drug Nifedipine
August 2021
Patients taking the widely prescribed calcium channel blocker nifedipine (PROCARDIA, PROCARDIA XL) should be aware that it has clinically important interactions with many other prescription medications.
Important Drug Interactions for the Abnormal Heart Rhythm Drug Amiodarone
July 2021
Patients taking the commonly prescribed abnormal heart rhythm drug amiodarone should be aware that it has clinically important interactions with many other prescription medications.
Important Drug Interactions for the Antibiotic Erythromycin
June 2021
Patients taking the commonly prescribed antibiotic erythromycin should be aware that it has clinically important interactions with many other prescription medications.
Overview of the Blood Thinner Rivaroxaban (XARELTO): An Update
May 2021
Learn why we have designated rivaroxaban, one of the so-called “novel” oral anticoagulants (blood thinners), as Do Not Use.
Important Drug Interactions for the Seizure Drug Carbamazepine
March 2021
Patients taking the commonly prescribed epilepsy drug carbamazepine (CARBATROL, EPITOL, EQUETRO, TEGRETOL, TERIL) should be aware that it has clinically important interactions with numerous other prescription and over-the-counter medications.
Overview of the Questionable Drug Andexanet (ANDEXXA)
February 2021
Andexanet (ANDEXXA) received accelerated approval from the FDA for emergency reversal of life-threatening or uncontrolled bleeding caused by the use of two new oral anticoagulants: apixaban (ELIQUIS) and rivaroxaban (XARELTO). Learn why we have designated andexanet and these two anticoagulants as Do Not Use.
Important Drug Interactions for the Calcium Channel Blocker Diltiazem
December 2020
Patients taking the widely prescribed calcium channel blocker diltiazem (CARDIZEM, CARTIA XT, TAZTIA XT, TIAZAC) should be aware that it has clinically important interactions with many other prescription medications.
Important Drug Interactions for the Stomach-Acid–Suppressing Drug Omeprazole
October 2020
Patients taking the commonly used stomach-acid–suppressing drug omeprazole should be aware that it has clinically important interactions with many other prescription medications.
Important Drug Interactions for the Anticoagulant Warfarin
August 2020
Patients taking the commonly used blood thinner warfarin (COUMADIN, JANTOVEN) should be aware that it has clinically important interactions with numerous other prescription and over-the-counter medications, as well as some dietary supplements.
Important Drug Interactions for the Antibiotic Azithromycin
July 2020
Patients taking the commonly prescribed antibiotic azithromycin (ZITHROMAX) should be aware that it has clinically important dangerous interactions with many other prescription medications.
Important Drug Interactions for Cholesterol-Lowering Drug Simvastatin
June 2020
Patients taking the commonly prescribed cholesterol-lowering drug simvastatin (FLOLIPID, VYTORIN, ZOCOR) should be aware that it has clinically important interactions with many other prescription medications.
Drug-Induced Liver Injury
May 2020
There are more than 1,000 prescription and over-the-counter medications, as well as certain herbal and dietary supplements, that are implicated in liver injury, and the list continues to grow.
Important Drug Interactions for the Antibiotic Clarithromycin
April 2020
Patients taking the commonly prescribed antibiotic clarithromycin (BIAXIN XL) should be aware that it has clinically important interactions with many other prescription medications.
Commonly Used Oral Drugs That Can Cause Eye Problems; Second of a Two-Part Series
February 2020
In this second of a two-part series, we review some of the many commonly prescribed medications that can damage your eyes and the steps that you can take to protect yourself from these adverse effects. The first part in this series appeared in our December 2019 issue.
Important Drug Interactions for Immune-Suppressing and Cancer Drug Methotrexate
January 2020
Patients taking the commonly prescribed drug methotrexate, which is used to treat certain autoimmune diseases and several types of cancer, should be aware that it has clinically important interactions with many other prescription and over-the-counter medications.
Important Drug Interactions for the Antifungal Drug Fluconazole
December 2019
Patients taking the commonly prescribed antifungal drug fluconazole (DIFLUCAN) should be aware that it has clinically important interactions with many other prescription medications. Some of these interactions can lead to an increased risk of fatal heart rhythm abnormalities.
Numerous Drugs Have Dangerous Interactions with Alcohol
August 2019
Most U.S. adults drink alcohol at least occasionally. Many also take prescription or over-the-counter drugs that have the potential to inter¬act adversely with alcohol. Avoid serious harm by knowing which drugs should not be taken in combination with alcohol.
Taking These Medications With Grapefruit Can Be Dangerous!
June 2019
Read about the many prescription drugs that can interact in dangerous ways with grapefruit or grapefruit products.
Study Reveals Increased Risk of Bleeding, Stroke from Combined Use of Oral Blood Thinners and NSAIDs
March 2019
Millions of Americans take anticoagulants on a long-term basis to prevent the formation of potentially harmful clots. Learn why such patients should avoid using nonsteroidal anti-inflammatory drugs.
Important Clopidogrel (PLAVIX) Drug Interactions
January 2019
Read about the many prescription and over-the-counter medications that can interact in dangerous ways with clopidogrel, a widely used anti-platelet drug.
Question & Answer
October 2018
Several readers have asked us whether the FDA’s recent approval of a drug that reverses the anticoagulant effect of apixaban (ELIQUIS) and rivaroxaban (XARELTO) alters our classification of these two drugs as Do Not Use. Read our answer.
Do Not Use the New Oral Blood Thinner Apixaban (ELIQUIS)
June 2018
Apixaban is a new oral anticoagulant (blood thinner) that was first approved by the FDA in 2012 for decreasing the risk of blood clots in certain patients. Find out why older anticoagulant drugs, such as warfarin (COUMADIN, JANTOVEN), are a better choice.
FDA: Drug for Treating High Blood Potassium Levels Should Not Be Combined with Other Medications
March 2018
Last year, the FDA warned that a drug used to treat high blood potassium levels can interfere with the absorption of many other oral medications. Learn the name of this drug and how to take it safely when using other drugs.
Do Not Use the New Blood Thinner Edoxaban (SAVAYSA)
November 2017
Learn why edoxaban, one of the new blood thinners approved by the FDA, is not the best option for preventing dangerous blood clots in patients with atrial fibrillation.
News Brief for October 2017
October 2017
In this month’s news brief, we report on the FDA’s recent decision to partially grant a petition from Public Citizen to require the addition of a warning about a dangerous drug-drug interaction to product labeling of repaglinide-containing diabetes medications.
Drugs That Are Most Likely to Land Patients in the Emergency Room
June 2017
Many adverse drug reactions are severe enough to cause serious injury, hospitalization and even death. Find out which outpatient medications are most likely to cause adverse events that necessitate a visit to the emergency room.
Is XARELTO Really the 'Right Move' for Patients With Blood Clots or Risk for Stroke?
April 2016
If you watch TV, you likely have seen ads touting the advantages of the new oral antico-agulant (blood thinner) rivaroxaban (XARELTO). Learn why we have designated this drug as Do Not Use for Seven Years (until at least July 2018).
Health Canada Warns of Dangerous Drug Interaction
January 2016
Learn why Health Canada, an agency similar to the Food and Drug Administration, warned Canadian consumers not to combine repaglinide-containing diabetes medications (PRANDIN or PRANDIMET) with the anti-platelet drug clopidogrel (PLAVIX).
Many Atrial Fibrillation Patients With Lowest Stroke Risk Receive Unnecessary Blood Thinners
December 2015
A recent study revealed that some cardiologists prescribe blood thinners to atrial fibrillation patients who don’t need them because their risk of stroke is very low. Read this article to learn who these patients are.
New Study Reveals Many Patients at Risk for Dangerous Alcohol-Drug Interactions
July 2015
Recent research revealed that many patients consume alcohol while using drugs that may can cause dangerous side effects when combined with alcohol. Read this article to learn about the many ways alcohol can adversely interact with prescription and over-the-counter medications.
Questions & Answers for March 2015
March 2015
In a new feature that will appear periodically in issues of Worst Pills, Best Pills News, we respond to some selected questions posed by our readers. In this month’s issue, we respond to questions regarding (a) whether the widely advertised drug adalimumab (HUMIRA) is a new wonder drug, and (b) what should you do if you are already taking rivaroxaban (XARELTO).
Adding NSAIDS or Aspirin to Anticoagulants Increases Bleeding Danger
December 2014
If you are one of the millions of patients in the U.S. who take blood thinners on a long-term basis to prevent potentially harmful clots in the heart, veins or arteries, read this article to learn why you should avoid taking NSAIDS or aspirin unless absolutely necessary.
New Atrial Fibrillation Treatment Guidelines Released
August 2014
Atrial fibrillation is one of the most common heart rhythm disorders, afflicting more than 2.7 million Americans. Learn about the most recent guidelines for treating this disorder, issued by the American College of Cardiology and the American Heart Association, and about Public Citizen’s Health Research Group’s assessment of those guidelines.
Genetic Tests Not Useful for Managing Warfarin Dosing, According to New Studies
July 2014
In 2007, the FDA enthusiastically suggested that newly available genetic tests would help doctors select the best dose of warfarin — one of the oldest and most widely prescribed blood thinners (anticoagulants) — for individual patients. Find out why the FDA’s enthusiasm about the promise of genetic testing in the management of warfarin dosing was premature and overstated.
Important Information to Know About Clopidogrel
June 2014
Clopidogrel is a widely used drug for reducing the risk of a new heart attack or stroke or cardiovascular death in patients who have had a recent heart attack, stroke or established pe-ripheral vascular disease. This article provides a detailed overview of the drug, including potential serious side effects and important precautions to follow when taking the drug.
More on the New Stroke Prevention Drugs
May 2013
An update on last month's article about three relatively new, widely used stroke prevention drugs: dabigatran (PRADAXA), rivaroxaban (XARELTO) and apixaban (ELIQUIS).
Emerging Risks With New Stroke Prevention Drugs
April 2013
Learn about three new drugs to prevent stroke – so new that their risks relative to those of a much older drug, warfarin (Coumadin), are unknown.
Troubling New Drug Approvals in 2012
March 2013
Find out which drugs approved in 2012 have risks greatly exceeding their benefits or no meaningful benefits. If you are using any of the DO NOT USE drugs reviewed in the article, talk to your doctor before stopping their use.
Update on Grapefruit Juice-Drug Interactions
July 2012
This article updates and expands our earlier list of drugs that can have harmful interactions with grapefruit juice. The list now includes 82 different drugs.
Applying the Life-Saving 7-Year Rule: An Antiarrhythmic and 3 Anticoagulants
April 2012
Find out why you should not use four recently approved heart drugs — dronedarone (MULTAQ), prasugrel (EFFIENT), dabigatran (PRADAXA) and rivaroxaban (XARELTO) — for at least seven years.
Risk of Bleeding and Use of Antidepressants After Heart Attack
March 2012
The article discusses why taking certain antidepressants after a heart attack may increase the risk of bleeding. Find out which ones are the culprits.
Inadvertent Adverse Reactions With Commonly Used Drugs
January 2012
Find out how to prevent emergency hospitalizations from two commonly used drugs, warfarin (COUMADIN) and clopidogrel (PLAVIX). There are approximately 33,000 emergency hospitalizations a year from warfarin alone. This article includes a list of more than 50 drugs that can have harmful interactions with warfarin and/or clopidogrel.
What Should People Do if They Miss a Dose of Their Medicine?
May 2011
This article, adapted for U.S. patients from an excellent review of the topic in the U.K., gives answers as to what course of action to follow if you miss a dose.
Bupropion Drug Interactions
October 2010
Bupropion is used to treat depression (brand name: WELLBUTRIN) and to aid smoking cessation (brand name: ZYBAN). The drug has a number of potentially dangerous interactions, some of which are quite different from typical antidepressant interactions.
Risk of Serious Gastrointestinal Bleeding With Newer Antidepressant Drugs
April 2010
This article discusses the greatly increased risk of bleeding with some widely-used antidepressant drugs and provides information that the FDA has not yet required be included in the patient Medication Guides for these drugs.
Herbal Medicines for Menopausal Symptoms? Hang Onto Your Wallet and Your Health
August 2009
The article reviews published evidence of safety and effectiveness for five herbal supplements widely used for treating menopausal symptoms. There is no convincing evidence that any of the herbal supplements promoted for relief of menopausal symptoms is beneficial. In addition, as discussed in the article, many of them have serious safety problems.
Muscle Damage from Interactions Between Statins and Other Commonly Prescribed Drugs
July 2009
The article lists 38 prescription drugs that can harmfully interact with statin drugs. The article also advises that No matter what statin you are taking and regardless of any interacting drugs, you should notify your prescriber immediately if you develop muscle pain, weakness or a darkening of your urine. .
What Aspirin Dose Is Safest and Most Effective for Preventing Heart Disease?
May 2009
This article discusses the fairly narrow range of daily aspirin doses most safe and effective for preventing heart disease.
Possible Interaction Between Cranberry Products and Widely Used Blood-Thinner Warfarin (COUMADIN)
April 2009
This article adds other substances, cranberry products, to the long lists of drugs we have previously stated should not be used with the important blood thinner, warfarin (COUMADIN).
Dangerous Interaction Between Heartburn Drugs and Clopidogrel (PLAVIX)
March 2009
This article describes how and why people using both PLAVIX, a drug that prevents blood clotting, and heartburn drugs such as NEXIUM had a 27 percent increased risk of heart attacks compared with people using PLAVIX alone.
Drug Interactions: Warfarin (COUMADIN)
December 2007
This article explains how to understand the International Normalized Ratio (INR), a test applied to a sample of a patient’s blood to determine how “thin” it is when you are using the blood thinner COUMADIN (warfarin). In addition, the article lists more than 50 drugs or dietary supplements that can interact harmfully with COUMADIN to cause the blood to be too thin (abnormal bleeding) or not thin enough which could result in lessening the effect of COUMADIN in stopping blood clot formation.
FDA Issues New Warnings For Muscle Spasm Drug Tizanidine (ZANAFLEX)
August 2007
The muscle spasm drug tizanidine (ZANAFLEX) combined with certain other drugs could cause serious complications such as drowsiness and can dramatically lower blood pressure, according to the Food and Drug Administration (FDA). The article lists 20 drugs to avoid if you are using Zanaflex so that you avoid these potentially dangerous interactions.
FDA-Approved Drug Information Now Required For The Blood Thinner Warfarin (COUMADIN)
December 2006
The Food and Drug Administration (FDA) announced October 10 that an agency-approved Medication Guide, which provides information about drug safety, will now be required to accompany all new and refill prescriptions for the blood thinner warfarin (COUMADIN). Warfarin can interact dangerously with a number of other drugs, dietary supplements and vitamins, but these products are inexplicably not listed in the Medication Guide. The details of these serioius interactions can be found at Worstpills.org or in our book, Worst Pills, Best Pills.
Adding Clopidogrel to Aspirin Offers No Benefit in Preventing Heart Attacks or Strokes
May 2006
If you have had a previous heart attack or stroke or have blood vessel disease, you should be on aspirin treatment rather than clopidogrel with or without aspirin. You should only take clopidogrel if you cannot tolerate aspirin.
Serious GI Toxicity With The Heart Drug Clopidogrel (PLAVIX)
March 2005
If you are now taking clopidogrel and do not have a severe allergy to aspirin, contact your doctor and discuss switching from clopidogrel to low dose aspirin plus a PPI.
Revisiting Clopidogrel (PLAVIX) Plain Aspirin Still Preferred in Preventing Stroke, Heart Attack and Blood Clots
January 2005
If you have had a previous heart attack, stroke, or have blood vessel disease you should be on aspirin treatment rather than clopidogrel unless you cannot tolerate aspirin, or aspirin treatment has failed. If you are now taking ticlopidine and cannot take aspirin, talk to your doctor about clopidogrel.
Drug Interaction Reminder: Fluoroquinolone Antibiotics and the Anticoagulant (Blood Thinner) Warfarin (COUMADIN)
September 2004
You should consider that all fluoroquinolone antibiotics have the potential to interact with warfarin and your physician should be ordering blood tests to monitor the status of your blood clotting if one of these antibiotics is needed and you are using warfarin. This is the safest thing to do.
Grapefruit Juice and Prescription Drugs: Some Dangerous Interactions
February 2004
The January 5th issue of the Medical Letter, a widely respected source of independent information about pharmaceuticals and dietary supplements, has a review of the increasingly researched problem of the interaction between grapefruit juice and many prescription and over-the-counter drugs. Like most interactions between chemicals in the body, this one involves the impairment, by grapefruit juice, of the body’s ability to metabolize many drugs, leading to higher than expected — and sometimes dangerous — levels of these drugs.This article lists the drugs.
New Safety Labeling Changes for Anticoagulant Warfarin (COUMADIN)
September 2002
Several new safety labeling changes have been required by the Food and Drug Administration (FDA) for the widely used anticoagulant drug warfarin (COUMADIN). These changes to the drug’s professional product labeling, or “package insert,” were made in May 2002. The article discusses the changes.

ADDITIONAL INFORMATION FROM PUBLIC CITIZEN
Petition to the FDA to Require a Warning About a Dangerous Drug Interaction Between Clopidogrel (Plavix) and Repaglinide (Prandin) in the Label for Both Drugs (HRG Publication #2354)
Public Citizen petitions the Food and Drug Administration (FDA) to require that the labels of the anti-clotting drug clopidogrel (Plavix) and the diabetes drug repaglinide (Prandin) warn doctors and patients that taking the drugs together can cause dangerously low blood sugar levels. The petition also asks that the drugs’ labels include a statement that the two drugs should never be taken together under any circumstances.
Public Citizen Petition to FDA to Warn Against Prolonged Use of Clopidogrel (Plavix) in Cardiac-Stent Patients Because of Lethal Side Effects, No Benefit (HRG Publication #2149)
Public Citizen petitions the Food and Drug Administration to warn patients and doctors that taking the widely prescribed drug clopidogrel (brand name: Plavix) for more than a year after having a drug-eluting stent implanted can lead to potentially fatal bleeding without providing further benefits.
Letter to FDA Opposing Approval of Rivaroxaban (Xarelto) for Anticoagulation Therapy in Patients With Atrial Fibrillation (HRG Publication #1974)
We strongly oppose FDA approval of Johnson & Johnson’s NDA for rivaroxaban for the prevention of stroke and systemic embolism in patients with nonvalvular atrial fibrillation, a condition for which two proven therapies already exist.