What causes Heroin withdrawal?
The neuroadaptation that we refer to as tolerance often results in rebounding when the substance is withdrawn. The withdrawal symptoms tend to be the opposite of effects produced by the drug. “Thus, withdrawal from a depressant drug will give rise to brain excitation as adrenergic neurons that have been unnaturally inhibited by a drug such as heroin in its absence become hyperactive and cause anxiety, shaking, and cold sweat” (Royal College of Psychiatrists 1987). Heroin depletes the neurotransmitter dopamine, and in withdrawal, the dramatic increase in dopamine activity intensifies other unpleasant symptoms. Physicians often use clonidine, a non-addicting drug, to slow down these neurons and thereby relieve withdrawal symptoms. Withdrawal symptoms peak in twenty-four to forty-eight hours and subside in about a week, although the psychological symptoms may persist indefinitely.
Children born to addicted mothers, in addition to having a host of other physical problems, such as small size, anemia, heart disease, hepatitis, and pneumonia, also suffer from withdrawal symptoms. The National Institute on Drug Abuse reports that infants who are born to heroin-abusing mothers frequently suffer from neonatal abstinence syndrome, withdrawal symptoms that may require medication.
Symptoms of Heroin withdrawal
• Muscular pain
• Abdominal cramps
• Excessive Sweating
• Breathing problems
• Involuntary muscular spasms
Comparison between administration and withdrawal effects: 
|Administration effects||Withdrawal effects|
|Decreased body temperature||Increased body temperature|
|Decreased blood pressure||Increased blood pressure|
|Pupil constriction||Pupil dilation|
|Drying of secretions||Tearing, runny nose|
|Decreased sex drive, impotence||Spontaneous ejaculation/orgasm|
 S. Maisto, et. al., “ Drug Use and Abuse 6th Edition” (Wadsworth, 2011), page 248 – 249
Duration of Heroin withdrawal
Withdrawal symptoms usually peak in intensity in the first 24 to 48 hours after the addict stopped taking the drug. Under the right medical guidance, the signs and symptoms subside in about a week, although the psychological symptoms may persist indefinitely.
Heroin Withdrawal Timeline
Heroin is a short-acting drug, meaning that it takes effect rapidly but also leaves the bloodstream quickly. The authorities estimate that generally, heroin withdrawal symptoms start within 6-12 hours of the last dose, peak in 2-3 days, and last 5-10 days in total.
Detox is considered the most efficient method of removing heroin (and many other drugs) from the body. The medical detox starts before heroin completely leaves the system. It usually takes between 5 and 7 days.
The detoxing period differs from one addict to another. For someone who is more heavily dependent on heroin, detox may last a little longer, up to 10 days. Medical detox may use medications and therapy to help the body and brain recover from heroin’s effects.