Prescription and Illicit Drug Abuse

Illicit Drug Abuse

What is Addiction?

Addiction is a chronic disease in which a person craves, seeks, and continues to use a legal (medication, alcohol, tobacco) or an illicit (illegal) drug, despite harmful consequences. People who are addicted continue to abuse a substance even though they know it can harm their physical or mental health, lead to accidents, or put others in danger.

The Role of Dopamine

Generally, people take illicit drugs to feel good or feel better than they felt before. This feeling of pleasure, or “high,” that a person gets from taking a drug comes from large, rapid increases in dopamine, a brain chemical. We all get a dopamine “rush” from things that we normally enjoy (such as eating good food or listening to our favorite music). Illicit drugs cause a much more intense and longer lasting increase in dopamine. Repeated exposure to large, drug-induced dopamine surges dulls the dopamine system’s response to everyday stimuli. So, the things we normally enjoy are no longer pleasurable, and even the effects of the drug aren’t as strong as they once were.

Other Effects on the Brain

But drug abuse doesn’t just affect the pleasure pathway. It also disrupts brain areas involved in memory/learning and control over behavior, which is why addicted people continue to use drugs, even though they know it is harmful, and is also why it is so difficult to stop, even when they want to.

For more on drugs and the brain, see “Drugs, Brains and Behavior: The Science of Addiction.”

Abuse Growing Among Older Adults

Although use of illicit (illegal) drugs is relatively uncommon among adults over age 65, there has recently been an increase in the percentage of people 50 and older abusing illicit drugs. In fact, the number of current illicit drug users aged 50-59 more than tripled between 2002 and 2012, from 900,000 to more than 3.0 million. More older adults are also seeking treatment for substance abuse and having increased hospitalizations and visits to emergency rooms (up more than 130 percent in 55-64 year-olds from 2004 to 2009) related to illicit drug use.

Baby Boomers Driving the Trend

These patterns and trends partially reflect the aging of the baby boomers (people born between 1946 and 1964). This could be for two reasons: (1) there were more people born in that generation and therefore there are now more people in that age group than before; and (2) baby boomers were more likely than previous generations to use illicit drugs in their youth, which is a risk factor for later use.

Which Illicit Drugs Are Abused?

While it is relatively rare for adults over 65 to have ever used illicit drugs, baby boomers (adults in their 50s and early 60s) are more likely to have tried them. Greater lifetime exposure could lead to higher rates of abuse as baby boomers age. The most common drugs of abuse include the following

  1. marijuana
  2. illegal opioids, such as heroin
  3. illegal stimulants, such as cocaine
  4. hallucinogens, such as LSD


Marijuana, made from the cannabis plant, is the most abused illicit drug among people 50 and older. It is used for its relaxing properties but can have several negative effects, including slowed thinking and reaction time, impaired memory and balance. It can also lead to paranoia and anxiety.

Although under federal law, marijuana is illegal to use under any circumstance, in some states doctors are allowed to prescribe it for medical use. However, solid data on marijuana’s health benefits is lacking, and for smoked marijuana many health experts have concerns about the potential negative effects on the lungs and respiratory system. The U.S. Food and Drug Administration has approved two medications chemically similar to marijuana to treat wasting disease (extreme weight loss) in people with AIDS and to lessen symptoms associated with cancer treatment, such as nausea and vomiting.

For more about marijuana and its effects on the body, see “DrugFacts: Marijuana."

Illegal Opioids

Opioids are powerful drugs that at first cause feelings of euphoria, then periods of drowsiness. They can also slow breathing. Some opioids are legal and prescribed by a doctor. Others, like heroin, are illegal. All types of opioids can be addictive and can lead to death if too much is taken (overdose).

For more about heroin and its effects on the body, see “DrugFacts: Heroin.”

Illegal Stimulants

Stimulants like cocaine make people feel more alert and energetic. But they can also cause elevated heart rate and blood pressure, paranoia, panic attacks, aggression, and other problems. They are very addictive and can lead to death if too much is taken (overdose). Some stimulants are legally prescribed by a doctor to treat health conditions. Other kinds -- including cocaine, MDMA (ecstasy), and methamphetamines -- are illegal.

For more about cocaine, see “DrugFacts: Cocaine."


Hallucinogens and dissociative drugs can greatly distort perceptions of reality, including making a person see, hear, and feel things that are not really there. Physical effects may include increased body temperature, heart rate, and blood pressure, sleeplessness, sweating, dizziness, and loss of appetite. Flashbacks and mood disturbances can also occur. This group of drugs includes LSD, peyote, psilocybin ("magic mushrooms"), and phencyclidine (PCP).

For more about hallucinogins, see “DrugFacts: Hallucinogins – LSD, Peyote, Psilocybin, and PCP."

Illicit Drugs and Aging

Age-related changes to our brains and bodies as well as typical diseases of aging could result in greater health consequences for older adults, even with lower levels of drug use. Drugs (both illicit and prescription) as well as alcohol affect older people differently than younger people because aging changes how the body and brain handle these substances. As people get older, the body goes through a number of changes and cannot break down and eliminate a drug as easily as it once did. As a result, the drug may remain in the body longer than it would in a younger person. Even a small amount can have a strong effect.

Effects on Health

Abuse of illicit drugs can make an older person’s overall health worse. For example, cocaine can cause heart problems even in young abusers. The effects on older people, who may already have heart disease, could be even more severe. In addition, people who abuse illicit drugs may be exposed to diseases they otherwise wouldn’t risk (such as HIV/AIDS or hepatitis, a liver disease). This is because drugs compromise judgment and can lead to harmful behaviors. Older adults who take illicit drugs or misuse prescription drugs also have a higher risk of accidents, falls, and injuries.

For more about the effects of drugs on health, see “Medical Consequences of Drug Abuse.”