Smoking Health Risks and Warfarin

By: Alere Staff

The risks of smoking cigarettes and how they affect the health of your lungs, skin and mouth are well-known. What you may not be aware of is that smoking actually harms nearly every organ of the body; tobacco smoke alone contains a deadly concoction of more than 7,000 chemicals with about 70 known to cause cancer.1 Cigarette smoking health side effects account for one of every five deaths each year as well as being the leading preventable cause of death in the United States.2  

Research has shown that smoking cigarettes can also cause stroke and coronary heart disease, both of which are also among the leading causes of death in the United States.2

Smoking and Heart Health 

A smoker is more likely than a non-smoker to develop stroke and coronary heart disease. For both conditions, smoking increases your risk by two to four times.2 Stroke risk increases because the act of smoking damages your blood vessels, making them thicken and grow narrower, reducing their ability to circulate blood and causing higher blood pressures.2 Smoking also increases heart disease and the chances of you experiencing a heart attack. Inhaled carbon monoxide is transferred to your bloodstream, decreasing the amount of oxygen carried in the red blood cells and increasing the amount of cholesterol build-up. This build-up can cause the arteries to harden, leading to a higher chance of heart disease and heart attack.3 The build-up can also increase clot formation and reduce the blood flow to your legs and skin, all of which can be prevented by not smoking.2

You don’t have to be a smoker to have cigarette smoke affect your health. If you are someone who lives around other smokers, secondhand smoke has been shown to also cause heart disease. Breathing in secondhand smoke has immediate harmful effects on your heart and blood vessels.4 The CDC estimates that secondhand smoke alone caused nearly 34,000 deaths related to heart disease each year during the years of 2005 to 2009, all of whom were adult nonsmokers within the United States.4 So while you yourself may not smoke, if you are a patient already managing a heart condition, living with and around smokers may have a harmful affect. 

Smoking, Nicotine and Warfarin 

Warfarin therapy is an effective agent in preventing stroke and the complications of cardiac events. However, if you both take warfarin and have a smoking habit, your risk of complications and cardiac events increases. Nicotine acts as a stimulant, increasing a person’s heart rate and the heart’s ability to contract. If you already have a heart condition, this can further harm that condition, putting you at risk for warfarin therapy complications. Another issue is that nicotine and other chemicals absorbed into the body through cigarette smoke can have an effect on the enzymes in the liver. In response, the liver makes more enzymes to eliminate the toxic substances while eliminating other things in the body like warfarin.5 This can result in the need for a warfarin dosage adjustment. While nicotine, one of the main ingredients in cigarettes, has no reported interaction with warfarin, the ingredient can still have an effect on your warfarin therapy. 

Stopping Smoking 

You may feel that quitting a habit like smoking is impossible. Nicotine is the most likely cause of cigarette addiction and you are not alone in fighting it. More people in the United States are addicted to nicotine than with any other drug and if you feel that quitting is more easier said than done, you’re correct. Research suggests that nicotine may be just as addictive as heroin, cocaine or alcohol.1 However, quitting a dependence on cigarettes can and does happen and you can never be too old to quit the habit.  According to the CDC, today there are more former smokers than there are current smokers.1 

The following treatments have proven effective for quitting:1

  • Counseling in person or over the phone.
  • Nicotine replacement products such as over-the-counter nicotine patches, gum and lozenges or prescription nicotine patches, inhalers or nasal sprays.
  • Prescription non-nicotine medications such as bupropion SR (also known as the Zyban® medication) and varenicline (also known as the Chantix® drug). 

Quitting smoking is a smart yet serious undertaking that should not be something you do on your own. Combining one or more of the different methods can make your chances of successfully quitting higher. Quitting is worth it too as it allows your body to start healing and lowers your risks for more serious heart complications.2

If you are a patient on warfarin, it is important to include your managing physician if you decide to quit smoking. Your INR results may need to be monitored closely during this time and while there is little evidence of an interaction with either the Chantix® medication or the Zyban®  medication, it is important to keep an eye on your INR levels as your body undergoes the withdrawals and changes.6,7 

What About E-Cigarettes? 

Electronic cigarettes, also known as e-cigarettes, are battery-operated products designed to deliver nicotine, flavor and other chemicals into your body. They turn the nicotine and other chemicals into a vapor that is inhaled by the user. Proponents of e-cigarette use often claim that e-cigarettes can help people quit smoking and aren’t as harmful as regular cigarettes. However, while other nicotine-containing smoking cessation products like inhalers and drugs are regulated by the Food and Drug Administration (FDA), e-cigarettes have yet to be watched on the federal level.8 So while the potential long-term benefits, risks and interactions with drugs like warfarin are currently unknown, it is important to keep an eye on how e-cigarettes can affect your INR. 

Smoking cigarettes has shown to be a major risk factor for all sorts of illnesses and conditions. Even just living in the vicinity of smokers can be hazardous to your health. Don’t let this preventable practice harm your heart and speak with your physician about what you can do to either stay healthy or quit. 


  1. Centers for Disease Control and Prevention. Quitting Smoking. February 17, 2016. Retrieved from:
  2. Centers for Disease Control and Prevention. Health Effects of Cigarette Smoking. February 17, 2016. Retrieved from:
  3. U.S. Department of Health and Human Services. The Health Consequences of Smoking: A Report of the Surgeon General. Atlanta: U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center for Chronic Disease Prevention and Health Promotion, Office on Smoking and Health, 2004.
  4. Centers for Disease Control and Prevention. Secondhand Smoke (SHS) Facts. February 17, 2016. Retrieved from the website:
  5. Pirmohamed, M. Drug metabolism. Medicine. Clinical pharmacology. Volume 36, Issue 7, July 2008, Pages 355–359.
  6. Burstein, A., et al. Lack of Pharmacokinetic and Pharmacodynamic Interactions Between a Smoking Cessation Therapy, Varenicline, and Warfarin: An In Vivo and In Vitro Study. The Journal of Clinical Pharmacology. Vol 47, Issue 11. Pg 1421-1429, Nov 2007.
  7. Sansone, R.A. and Sansone, L.A. Warfarin and Antidepressants - Happiness without Hemorrhaging. Psychiatry (Edgmont). 6(7): 24–29. July, 2009.
  8. Centers for Disease Control and Prevention. E-cigarettes: An Emerging Public Health Challenge. October 7, 2016. Retrieved from the website:

Chantix is a trademark of Pfizer. Alere is not affiliated or associated with the Pfizer company.

Zyban is a trademark of the GlaxoSmithKline group of companies. Alere is not affiliated or associated with the GlaxoSmithKline group of companies.