Smoking and Exposure to Second-hand Smoke Negatively Influences MS Disease Activity and Progression

Summary: Smoking is a known risk factor for the onset and progression of multiple sclerosis (MS). In this study, researchers found that not only smoking, but also exposure to second-hand smoke had a negative impact on disease progression in people living with MS. Those who continued smoking following an MS diagnosis were associated with higher risk of physical, psychological, and cognitive worsening and faster disease progression compared to non-smokers, highlighting the potential benefits of smoking cessation.  

Details: Smoking is a well-known risk factor for both MS onset and accelerated disease progression. In this study, researchers investigated the effect of smoking, second-hand smoke, and smokeless tobacco (also known as snuff) on disease progression, cognitive performance, and quality of life in people with MS. A total of 9,089 people with MS from the Swedish MS Registry were categorized based on tobacco exposure (i.e., never smoker, past smoker, current smoker, smokeless tobacco) at the time of MS diagnosis and were followed for up to 15 years post diagnosis. They studied changes in severity and disability over time by measuring the Expanded Disability Status Scale (EDSS) from the time of diagnosis and during follow-up.

Results: The study found that current smokers had higher EDSS scores at time of diagnosis compared to non-smokers, and both current and past smokers showed faster increases in EDSS scores over time compared to never smokers. Current smoking was also associated with greater risk of physical, psychological, and cognitive disability worsening compared to never smokers. Similarly, people with MS currently exposed to second-hand smoke were associated with higher EDSS scores at time of diagnosis compared to those who had never been exposed, and those currently exposed showed a faster EDSS progression. Smokeless tobacco users, often considered an alternative to smoking, was not associated with a higher disease activity or progression. Lastly, the study found that people who continued smoking after diagnosis had worse outcomes compared to non-smokers.

Impact: This study contributes to the growing body of knowledge on the impact of active and passive (second-hand) smoking as a risk factor for MS, as well as accelerated disease progression. This research helps to raise awareness and provide education about the risks associated with smoking and exposure to second-hand smoke specific to MS disease onset and progression. To learn more about how to quit smoking, or support a family member to quit, visit Tools for a smoke-free life through the Government of Canada.


Article published in Journal of Neurology, Neurosurgery & Psychiatry on March 31, 2023 – Influence of oral tobacco versus smoking on multiple sclerosis disease activity and progression. Link to article – here.

Additional Information:

Learn more about smoking and other risk factors of MS – here.