Acute withdrawal symptoms are physiological and psychological bodily manifestations that become apparent when chemical use is severely reduced or discontinued. Differing acute withdrawal symptoms are seen dependent upon which prescribed or illicit substance is withdrawn from the system. Some common symptoms that are seen across the spectrum include anxiety, insomnia, and loss of appetite. Acute withdrawal symptoms are seen when the substance is first discontinued and can continue for up to two weeks. The intensity and duration of the syndrome depends upon the specific substance, the length of time it has been used for, and the frequency of use.
The medical community regards acute alcohol withdrawal symptoms as some of the most dangerous. Often times, withdrawal from ethanol needs to be done in an inpatient hospital setting in order to prevent seizures and cardiovascular complications that can lead to death. Acute withdrawal symptoms from alcohol abuse start to manifest as early as six hours after the beginning of the decline of maximum intoxication. Some of the first signs of acute detoxification include severe anxiety, tremor, and insomnia. In patients who are only mildly alcohol-dependent, these symptoms may be the only ones experienced and usually subside within a few days without medical intervention. More serious acute withdrawal symptoms are seen in patients who are very dependent upon the substance and include seizures, heart attack, and a condition called delirium tremens (DT), which usually manifests as severe confusion and hallucinations.
Benzodiazepines, a class of drugs that includes sedatives like clonazepam and lorazepam, can cause acute withdrawal symptoms that are similar to those of alcohol. This similarity is due to both chemicals acting upon some of the same receptors in the brain, specifically those for the neurotransmitters gamma-aminobutyric acid (GABA) and glutamate. In the case of GABA, an inhibitory neurotransmitter, prolonged use of benzodiazepines causes its receptors to downregulate, meaning that the body does not have enough receptors to receive GABA, potentially causing severe agitation and seizures. The over-expression of glutamate, an excitatory neurotransmitter, causes acute withdrawal symptoms because its receptors upregulate, causing more of the substance to be active in the brain.
The abuse and sudden cessation of the use of opioid chemicals, like narcotic pain relievers and heroin, can cause severe acute withdrawal symptoms as well. The most common symptoms include muscle and bone pain, vomiting, and an insatiable craving for the drug being abused. More serious cases of the syndrome can result in convulsions and coma. While the reported deaths from acute opioid detoxification are significantly lower than those from alcohol, many patients are still advised to be treated in an inpatient setting due to the severity of the painful and distressing symptoms.