Does smoking age a smoker's skin on the inside too, or only on the outside?

Smoking visibly ages the skin: more wrinkles, loss of elasticity and uneven pigmentation. That is well documented. But the damage does not stop at the surface.

On the inside, smoking raises inflammatory markers in the blood considerably. This was shown in a study of more than 182,000 people across 22 populations: smokers had significantly higher levels of inflammatory and coagulation markers than people who had never smoked, and the more cigarettes smoked per day, the higher those levels. This kind of low-grade, chronic inflammation accelerates ageing throughout the entire body, including the deeper layers of the skin.

Tobacco smoke also damages the protective barrier of the skin and mucous membranes. That barrier keeps harmful substances out and regulates moisture and immune defence. When it is disrupted, it contributes to inflammatory diseases and accelerates the overall ageing of tissue.

The internal trail extends beyond the skin. Smoking accelerates atherosclerosis: the walls of arteries thicken and calcified deposits form in the coronary arteries. Even thirty years after quitting, that calcium score was still nineteen percent higher than in people who had never smoked. Inflammation and coagulation markers did gradually return to the levels seen in non-smokers after quitting, but that process also took approximately thirty years.

Whether smoking causes extra ageing of the inner skin layers independently of other organs is difficult to separate from the broader bodily damage. That distinction has not been separately quantified in the available studies. What is clear is that the ageing effects of smoking are not superficial -- they are present in the blood, the vessel wall and the cell.