Drug Use 101: Physical Dependence and Withdrawal
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Background
A daily coffee drinker suddenly deprived of their favorite beverage may find themselves drowsy and distracted, irritable, depressed, or suffering from an excruciating headache. These symptoms are a form of withdrawal resulting from physical dependence on a substance—in this case, caffeine. While it can be uncomfortable, physical dependence on caffeine is unlikely to affect a person’s life dramatically. Caffeine withdrawal tends to be relatively mild and short-lived, and returning to use comes without major health or legal consequences.
But people can experience physical dependence on a variety of substances, and the symptoms and consequences of that dependence vary according to a range of factors.
What are drug dependence and withdrawal?
Physical dependence is when a person’s body requires a particular substance to function optimally. Many substances—including legal, recreational, illicit, and prescription—can cause physical dependence with prolonged, consistent use. While physical dependence on a substance may be one aspect of a substance use disorder, its presence is neither necessary nor sufficient to make a diagnosis.
Withdrawal occurs when a person who is physically dependent on a substance abruptly tapers or ceases use, including missing a usual dose. Symptoms vary between substances and may be physiological, behavioral, and/or cognitive. Withdrawal can be acute (often occurring within hours of last use and persisting for a week or more) or chronic, although colloquial use of the term generally refers to the former.
How common is physical dependence on substances?
Rates of physical dependence vary by substance. For example, roughly half of regular coffee drinkers develop physical dependence on caffeine and experience withdrawal symptoms if they abstain, whereas an estimated 56 to 85 percent of regular nicotine users develop dependence that leads to withdrawal on abstention. Similarly, research suggests that 56 percent of people tapering antidepressant medications experience withdrawals, and nearly half of these individuals will have severe symptoms. The vast majority of people who regularly consume opioids develop physical dependence, although only about 8 percent develop an opioid use disorder.
Why do dependence and withdrawal matter?
The implications of dependence and withdrawal vary according to the substance involved. Substance dependence can be particularly harmful when withdrawal symptoms are severe, when the substance is difficult (or illegal) to access, or when its use is associated with health risks. For example, withdrawal from alcohol or opioids can be life threatening, and the powerful desire to relieve miserable opioid withdrawals can increase risk of overdose, needle sharing, and criminal activity. Similarly, nicotine dependence can be deadly when it drives a person to smoke combustible cigarettes. In turn, dependence is much less problematic when regulated products and medications are available. Reduced-risk nicotine and medications for opioid use disorder provide safer alternatives to combustible cigarettes and illicit opioids while preventing withdrawal.
Acute Withdrawal Symptoms for Select Substances
