Hello,
Yes, smoking is known to impair wound healing. Also, it would delay the scar attaining its maturity. In the initial phases of healing, the scar is red meaning it is immature and the strength is also less. With time, the color of the scar fades and it becomes whitish as it gets mature and acquires tensile strength. Therefore, stop smoking for at least a few months to hasten this process.

Smoking is a well known cause of delayed healing. It generally affects healing in the immediate post operative period as smoking leads to decreased oxygen supply to the wound by increased carbon dioxide levels and constriction of blood vessels leads to decreased blood supply to the wound. Apart from that various other chemicals in the smoke cause cell damage hence affects healing.

Any scar after either operation or trauma takes at least 9 months to one year to completely mature up.

In your case the redness of scar after 7 months of operation may be due to many factors, most common of them is that it may be due to scar is still immature and active healing process is still taking place but at abnormally high pace hence it is still red due to increased healing activity. Smoking delays the maturing of scars. hence I suggest that you should stop smoking, at least till the scar become mature, whitish and fades away. If the scar starts becoming thick and itchy it means abnormal healing is going on and must consult your operating surgeon. Meanwhile you should massage three to four time per day the scar by cold cream.
Dr Rajesh Kaushash
Cosmetic & Plastic Surgeon