Smoking and Drug Interactions

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KEY POINTS

• Smoking tobacco causes changes in the way that medicines work in your body. You may need more medicine to get the same effect, or you may have greater risk of side effects.
• Tell all healthcare providers who treat you about all of the products you are taking, and if you smoke.
• If you are a smoker, talk to your healthcare provider about ways to quit.

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What is a drug interaction?

A drug interaction is a change in the way that a medicine works when you take it with another medicine, or with vitamins, natural remedies, alcohol, or tobacco. If you have a drug interaction:

• The drug may not work as well as it should.
• The drug’s effect may be increased.
• You may have different or increased side effects.

What is the cause?

In most cases, it is tobacco smoke (not nicotine) that causes the interactions. While most people think of smoking as affecting the lungs, it also affects certain chemicals called enzymes in your liver. These enzymes help the cells of your body work. If the liver enzymes are also affected by certain drugs, it changes the way the drugs work in your body. For example:

• Theophylline, a medicine used to treat asthma and COPD. Smokers need to take higher doses to get the same effect.
• Clopidogrel, a medicine used to prevent blood clots. People who smoke more than 10 cigarettes per day have a higher risk of bleeding when taking this medicine.
• Bendamustine, a medicine used to treat some kinds of cancer. If you smoke, the effects of this medicine may be decreased.

Starting or stopping smoking may cause drug interactions, and change the dose of the medicines you take. Even being around someone who smokes can cause changes in the way your body processes medicines.

How can I prevent drug interactions?

• If you are a smoker, talk to your healthcare provider about ways to quit. You might find it helpful to join a quit-smoking program, use nicotine patches or gum, or try one of the prescription medicines that can help you quit. These methods work best when they are used together, and under the supervision of your healthcare provider.
• Follow the directions that come with your medicine, including information about smoking, food, or alcohol. Make sure you know how and when to take your medicine. Do not take more or less than you are supposed to take.
• Try to get all of your prescriptions filled at the same place. Your pharmacist can help make sure that all of your medicines are safe to take together. Let the pharmacist know if you smoke, and ask if that affects your medicines.
• Keep a list of your medicines with you. List all of the prescription medicines, nonprescription medicines, supplements, natural remedies, and vitamins that you take. Tell all healthcare providers who treat you about all of the products you are taking, and if you smoke.
• Many medicines have side effects. A side effect is a symptom or problem that is caused by the medicine such as nausea or a fast heart rate. Ask your healthcare provider or pharmacist what side effects your medicines may cause and what you should do if you have side effects.

If you have any questions, ask your healthcare provider or pharmacist for more information. Be sure to keep all appointments for provider visits or tests.