Addiction Nicotine Use After You Quit How Quitting Smoking Can Impact the Medicines You Take By Terry Martin facebook twitter Terry Martin quit smoking after 26 years and is now an advocate for those seeking freedom from nicotine addiction. Learn about our editorial process Terry Martin Medically reviewed by Medically reviewed by Armeen Poor, MD on October 10, 2020 Armeen Poor, MD, is a board-certified pulmonologist and intensivist. He specializes in pulmonary health, critical care, and sleep medicine. Learn about our Review Board Armeen Poor, MD on October 10, 2020 Print Tim Robberts / Getty Images Table of Contents View All Table of Contents Overview Impacts Affected Prescription Drugs Caffeine Nicotine Consult Your Doctor Prescription drugs are known to interact with other drugs and certain foods, but they can also be affected by smoking—and smoking cessation. Overview Foods that we eat are broken down (metabolized) into nutrients that our bodies can use. This process starts with enzymes, which act as catalysts for the digestive process. There are many types of enzymes. Some of them help break down proteins, some work on carbohydrates, and others on fats. In a similar way, there are enzymes that metabolize prescription drugs. One of these enzymes, CYP1A2, is affected by some of the chemicals in cigarette smoke. These toxins, called PAHs (polycyclic aromatic hydrocarbons) are known to be some of the most potent carcinogens in tobacco smoke. Impacts When PAHs come in contact with CYP1A2 the enzyme becomes more active. This causes medicines that are broken down by CYP1A2 to be metabolized more quickly than they should be. As a result, smokers often require a higher dose than would normally be given. When smoking stops abruptly, such as going into the hospital where smoking isn't allowed or quitting cold turkey, CYP1A2 activity slows down and the larger dose can suddenly be too much. The chance of negative side effects of medications abruptly increases as well. It is important that medications be reviewed and possibly adjusted by the prescribing doctor when a person quits smoking. An Overview of Nicotine Withdrawal Affected Prescription Drugs As you can see from this list, a wide variety of medications are metabolized by CYP1A2. Some of them won't cause an adverse reaction following smoking cessation, but others can cause serious side effects if the dose isn't modified or adjusted once a person stops smoking. Don't hesitate to share your quit smoking journey with your healthcare team so that they can keep an eye on any changes you might be experiencing. Alosetron (Lotronex): Antidiarrheal used to treat irritable bowel syndrome Clozapine: Sedative drug used to treat schizophrenia Flutamide (Eulexin): Hormone-based chemotherapy medicine Fluvoxamine (Luvox): Used to treat obsessive or compulsive behaviors Frovatriptan (Frova): Used to treat migraine headaches Haloperidol (Haldol): Treats schizophrenia, acute psychosis, and is used for tics and vocal utterances of Tourette's syndrome Imipramine (Tofranil): Used to treat depression Melatonin: Over-the-counter supplement used for sleep Mexiletine (Mexitil): Antiarrhythmic used to treat irregular heartbeat Mirtazapine (Remeron): Antidepressant used to treat depression. Olanzapine (Zyprexa): Used for schizophrenia, bipolar disorder Propanolol (Inderal): Used to treat tremors, angina (chest pain), high blood pressure, heart rhythm disorders, and other heart or circulatory conditions. Also used to treat migraine headaches Ramelteon (Rozerem): Sedative used for insomnia Rasagiline (Azilect): MAOI and antidepressant that can be used to treat Parkinson's disease Ropinirole (Requip): Dopamine promoter that can be used to treat Parkinson's disease and restless leg syndrome Tacrine (Cognex): Used to treat Alzheimer's disease Theophylline: Long-term asthma control medication Tizanidine (Zanaflex): Muscle relaxant used to treat muscle spasms Triamterene (Dyrenium): Diuretic used for fluid retention and high blood pressure Zolmitriptan (Zomig): Triptan used to treat migraine headaches Caffeine Most ex-smokers will tell you that coffee had a much stronger effect on them after quitting smoking. The usual cup or two in the morning left them jittery and nervous. They'd chalk it up to the lack of nicotine, and that does play a role, but it probably had more to do with CYP1A2. Smokers metabolize caffeine at approximately four times the rate of non-smokers. It is no wonder that drinking the usual amount of coffee or other caffeinated drink is suddenly uncomfortable following smoking cessation. If you recently quit, you might try cutting your caffeine consumption by half and see how you feel. You can then reduce or increase based on that. Nicotine Nicotine in tobacco and in nicotine replacement therapy can also influence how the body is able to respond to some medications. Nicotine constricts blood vessels and may inhibit the absorption of insulin shots. Nicotine is a stimulant that raises heart rate and blood pressure. It may contribute to reduced sensitivity to medications used to treat the same. It is also associated with reduced sedation from benzodiazepines (tranquilizers) and less pain relief from some opioids. Consult Your Doctor If you take any prescription medicines and have stopped smoking (or you plan to), make an appointment with your doctor to review how your medications may be affected by smoking cessation. The good news is that quitting smoking will improve your health and vitality. You may even find that some medications can be eliminated once your body recovers from nicotine addiction. A Word From Verywell If you're ready to quit, use these quit smoking resources as a starting point. There is no time like the present to start work on making your dreams a reality. How to Quit Smoking for Good Was this page helpful? Thanks for your feedback! So you're ready to finally quit smoking? Our free guide can help you get on the right track. Sign up and get yours today. Sign Up You're in! Thank you, {{form.email}}, for signing up. There was an error. Please try again. What are your concerns? Other Inaccurate Hard to Understand Submit Article Sources Verywell Mind uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy. Australian Prescriber. Smoking and Drug Interactions. Pharmacy Times. Get to Know an Enzyme: CYP1A2. Speak to a Therapist for Addiction Advertiser Disclosure × The offers that appear in this table are from partnerships from which Verywell Mind receives compensation.