This is a little like comparing apples and giraffes. One may safely say a single cigarette will never kill you, but a hypodermic full of heroin just might.
That doesn’t mean cigarettes are safe, however, not by a long shot. Most medical professionals agree that cigarettes can be every bit as addictive as heroin. This means that withdrawal symptoms can be every bit as severe for a pack-a-day smoker as for any horse junkie jittering his way through the hee-bee jee-bees at a rehab clinic.
Much of it depends on the personality of the smoker, of course. Some people are simply more prone to addictive behaviors than are others.
These days, smoking cessation aids like the nicotine patch, gum and lozenges are available to help you quit smoking, but any way you look at it, it’s an uphill climb, and one requiring no small part of willpower on the part of the smoker.