Smoking just a few cigarettes a day can more than double a woman's risk of rheumatoid arthritis, research has shown.
Compared with never-smokers, women who puffed between one and seven cigarettes a day had a 2.31-fold higher chance of developing the disease.
Even 15 years after quitting the habit, the risk was nearly twice as high among former smokers. But the study did find that the likelihood of suffering rheumatoid arthritis reduced over time after giving up smoking.
Researchers in Sweden analysed data from 34,101 women aged 54 and 89, of whom 219 had rheumatoid arthritis (RA).
RA is an autoimmune disease caused by the body's immune system attacking the joints. It differs from osteoarthritis, which is the result of wear and tear and damage from injuries.
The study also found that RA risk increased with the length of time a woman had been smoking.
Smoking for 25 years raised the risk 1.60 times compared with smoking for one year.
Lead researcher Ms Daniela Di Giuseppe, from the Karolinska Institute in Stockholm, said: "Stopping smoking is important for many health reasons, including the increased risk of RA for smokers. But the clearly increased risk of developing RA, even many years after giving up, is another reason to stop smoking as soon as possible, and highlights the importance of persuading women not to start at all."
The findings are published in the online journal Arthritis Research & Therapy.
Women who had not been smoking for 15 years had a 30% lower risk of RA than women who quit only a year ago, the results showed.