Smoking's effects on sexual health

Smoking injures the ability of blood vessels to respond to sexual stimuli. Normally blood vessels release a substance known as nitric oxide during sexual stimulation, resulting in the opening of the floodgates. Smokers release less nitric oxide and the blood vessels open less readily, resulting in a flaccid erection. It is still unknown whether nicotine or other products of cigarette smoke cause all the effects related to vascular damage.

During an erection, blood flows into the penile arteries causing the veins which drain the penis to become compressed, preventing blood from leaving the penis. This process is significantly impaired by smoking. Less blood flows into the penis if the route is blocked by fatty deposits in the arteries, (atherosclerosis) caused by smoking. Acute vasospasm, contraction of the penile tissue, and restricted blood flow to the penis is a result of nicotine stimulation in the brain. The valve mechanism that traps blood in the penis is impaired as a result of nicotine in the blood stream. Some of the other male sexual dysfunctions cause by smoking cigarettes include: Reduced amount of ejaculate. Lower sperm count. Abnormal sperm shape. Impaired sperm mobility.

Cigarette smoking can also affect male fertility: smoking reduces the quality of semen. Men who smoke have a lower sperm count than non-smokers, and their semen contains a higher proportion of malformed sperm. By-products of nicotine present in semen of smokers have been found to reduce the motility of sperm.  One study found that sperm damaged by smoking may also result in more couples having baby girls than boys. The researchers suggest that the sperm cells carrying the Y chromosome are more vulnerable to the toxins in cigarette smoke.