Opium is derived from the dried latex of the opium poppy, Papaver somniferum. This raw material contains alkaloids, including the primary psychoactive compounds: morphine, codeine, and thebaine. When smoked, these alkaloids are rapidly absorbed into the bloodstream through the lungs. This delivers a potent concentration to the body and brain.
How Opium Interacts with the Central Nervous System
The effects of smoking opium begin at the molecular level within the central nervous system (CNS). Active alkaloids, such as morphine, function as opioid agonists. They chemically mimic the body’s natural pain-relieving compounds, endorphins, and bind directly to opioid receptors.
The binding is most prominent at the mu-opioid receptors, which are densely located throughout the brain and spinal cord. Activation of these receptors alters the release of various neurotransmitters, effectively disrupting normal communication pathways. This action results in a generalized depression of the CNS, leading to reduced sensitivity to pain and a slowing of bodily functions.
The mu-1 receptor subtype is associated with the pain relief, or analgesia, that opium provides. Opioids also bind to receptors in the limbic system, the emotional center of the brain, regulating mood and contributing to psychological effects. This binding alters pain perception, emotional processing, and autonomic functions.
Immediate Physical and Psychological Sensations
Because smoking provides rapid absorption, the effects begin almost immediately after inhalation. Users often report an intense feeling of well-being, a euphoric rush. This is swiftly followed by a deep sense of calm and profound physical relaxation.
The intensity of the relaxation can lead to a state known as “nodding,” where the user drifts between consciousness and a dreamlike sleep. This period is marked by analgesia. Accompanying these psychological changes are distinct physical manifestations that reflect CNS depression.
Miosis, or pinpoint pupils, is a characteristic physical sign, occurring because the drug stimulates the oculomotor nerve. Users may also experience initial episodes of flushing, nausea, or vomiting before the CNS-depressant effects take full hold. Motor functions become noticeably reduced, resulting in slurred speech, drowsiness, and an overall reduction in movement.
Risks of Acute Toxicity and Overdose
The most life-threatening danger associated with acute opium use is respiratory depression. Opioid alkaloids act directly on mu-opioid receptors in the brainstem, which is the control center for automatic functions like breathing. This action suppresses the body’s natural drive to breathe by blunting the response to rising carbon dioxide levels.
Smoking opium is hazardous because the rapid absorption into the lungs leads to a high peak concentration of the drug in the blood and brain. This quick onset can overwhelm the respiratory centers before a person can react. Breathing becomes progressively slower and shallower, eventually leading to hypoxemia, or a severe lack of oxygen.
Symptoms of an acute, life-threatening overdose include extreme sedation, an inability to be roused, and visible signs of hypoxia, such as blue discoloration of the lips and fingertips. If breathing stops entirely, the lack of oxygen will quickly cause cardiac arrest. This suppression of the body’s most basic survival reflex makes an opioid overdose a medical emergency.
Progression to Physical and Psychological Dependence
Repeated use of opium leads to the development of tolerance. Tolerance means the same dose of opium no longer produces the desired effect, compelling the user to consume larger amounts to achieve the initial sensations. This escalation in dosage increases the risk of toxicity and accelerates the body’s adaptation to the drug’s constant presence.
This physical adaptation is termed physical dependence, where the body requires the opioid simply to function normally. If use is suddenly stopped, the body reacts with withdrawal symptoms. These symptoms often resemble a severe case of the flu, including:
- Intense muscle and bone pain
- Gastrointestinal distress
- Sweating
- Anxiety
The onset of withdrawal can begin six to twenty-four hours after the last dose, depending on the specific alkaloid concentrations. The painful and uncomfortable nature of these symptoms creates a powerful imperative to continue using the drug. This cycle of needing the drug to prevent withdrawal is a primary driver in the progression toward an opioid use disorder.