If you want to have dark circles under the eyes, a skinny gaunt appearance, possible weight problems and early wrinkles then using drugs is the best way to get there. Whether one is abusing alcohol, taking too many prescriptions or using illicit drugs like cocaine, heroin or methamphetamine these substances take a real toll on physical appearance.
Addicts may gain a ton of weight with drug use or may lose weight quickly and be unable to gain no matter what they eat. Because personal hygiene suffers one may be too “revved up” or too lethargic to bathe, take care of their teeth or skin or even get treated when they are ill. Unfortunately the focus of life becomes getting and using drugs.
As a result personal appearance and health is neglected. Here are the top ways that drugs and alcohol affect physical appearance.
Personal Grooming
As stated above when drugs and alcohol take center stage, personal grooming goes out the window. An addicted person may look un-
kept, disheveled or even like a completely different person than when they where sober. Some will stop showering or bathing. Others will not fix themselves up and go around with tangled hair, no make-up and old, worn clothes.
Dark circles under the eyes are common with all types of drugs. With substances like alcohol one can experience a period of weight gain. With drugs like cocaine, methamphetamine and even heroin a person may lose a ton of weight.
Condition Of The Teeth
Because drugs rob the body of nutritional deficiencies gum disease, cavities and even rotted teeth are common for those with abuse problems. Some will even lose teeth or become more prone to getting infections of the mouth in general.
Problems With The Skin
When one uses drugs or abuses alcohol the skin will also react negatively. Acne breakouts are more common and some will get redness in the face after prolonged use.
A Weakened Immune System
Those who are addicted to drugs often get sick more easily than others and are unable to fight off both major and minor infections. 
Upper respiratory infections are especially common for men or women who smoke or inhale drugs. Things like deep coughs as well as nosebleeds, earaches and sore throats are also common.
Drugs are also shown to cause certain cancers, organ damage, cirrhosis (with alcohol use) and kidney and liver problems for users.
Mental Effected Also Affect Physical
Mental effects such as a slower reaction time, problems with memory and reasoning can also affect the physical appearance and actions. A drug addict may overreact easily, not react at all or just be confused. Their eyes could be glazed over and red and they could be moving more slowly. On the other hand those using speed may be running around in circles with no real purpose to the confusion.
The more a person uses drugs the more difficult it is to care for themselves physically. If you have a loved one or family member and see a deteriorating physical appearance and have reason to believe that drugs are to blame, get them help.
Source: http://www.ehow.com/about_4812673_physical-effects-drug-abuse.html
