Both smoking and quitting smoking can affect how some medicines or substances like caffeine work in your body.
If you smoke, or if you are thinking about quitting or smoking less, talk to your doctor or pharmacist about the medicines you take. They can make sure you are taking the right dose and help you manage any uncomfortable symptoms.
Tobacco smoke and medicine
Tobacco products you smoke, like cigarettes and cigars, can change how some medicines work in your body. In most cases, it is the tobacco smoke—not the nicotine—that affects the medicines.
This means that if you smoke tobacco products, you may need a higher dose of some medicines than a person who doesn’t smoke.
Quitting smoking and medicines
Quitting smoking can slow down how your body uses some medicines. So if you keep taking the same dose as you did before you quit smoking, you could feel unwell or notice changes in the way your medicine is working.
This can happen with the following types of medicines:
- medicines for mental health concerns, like clozapine, fluvoxamine, and lorazepam
- diabetes medicines, like insulin
- stroke prevention medicines, like warfarin, heparin, and clopidogrel
- asthma medicines, like theophylline and inhaled corticosteroids
If you use any medicines and you want to quit smoking or smoke less, talk to your doctor or pharmacist about any medicines you take. They will help you understand what changes could happen and help you feel well as your body gets used to being smoke-free.
Tobacco smoke and caffeine
When you quit smoking or smoke less, your body breaks down
caffeine more slowly. This makes the effects of caffeine stronger, causing you to feel unwell. For example, you may feel shaky, sick to your stomach, anxious, or irritable.
There are ways to lower the risk of these symptoms so it’s easier for you to quit smoking or smoke less. Talk to your doctor or pharmacist to learn more.
Caffeine from foods and drinks
Caffeine is in many foods and drinks, like soda pop, coffee, tea, chocolate, and energy drinks.
Before you change how much you smoke, start lowering your daily caffeine from foods and drinks by about half. For example, if you normally drink 2 cups of coffee a day, drink 1 cup. Another option is to replace some your caffeinated drinks with decaffeinated options, like swapping out 1 cup of regular coffee for 1 cup of decaffeinated coffee.
Having less caffeine can help you avoid the uncomfortable symptoms of too much caffeine in your body.
Caffeine in medicines and supplements
Some medicines or dietary supplements have caffeine.
If you are taking medicines or supplements that have caffeine, do
not stop taking them or change your dosage until you talk to your doctor or pharmacist. They can make sure you are taking a safe amount as you quit smoking or smoke less.
Note: Tobacco refers to commercial tobacco products, like cigarettes sold in stores. It does not include the traditional tobacco used by First Nations and some Métis groups for ceremonial purposes and as a sacred medicine.
