Q.Drugs like LSD, barbiturates, amphetamines, etc., are used as medicines to help patients with mental illness. However, excessive doses and abusive usage are harmful. Enumerate the major adverse effects of such drugs in humans.

Drugs like LSD, barbiturates, and amphetamines are prescribed in controlled doses for specific mental health conditions, but their misuse—especially in high doses or without medical supervision—causes serious harm. The NCERT textbook lists several major adverse effects.

• LSD (Lysergic Acid Diethylamide) is a hallucinogen. Its abuse can lead to hallucinations, delusions, and severe mental disturbances that may persist even after the drug is stopped. It can also cause flashbacks where the user re-experiences the drug's effects long after use.

• Barbiturates are depressants that slow down brain activity. Overuse can cause impaired motor coordination, slurred speech, confusion, and dependence. In high doses, they can depress the respiratory centre in the brain, leading to coma or death. …

The story of these drugs is a cautionary tale about the thin line between healing and harm. LSD, barbiturates, and amphetamines were originally developed to treat specific mental health conditions — LSD for psychotherapy, barbiturates as sedatives and anaesthetics, and amphetamines for narcolepsy and attention disorders. But when taken in doses beyond what is prescribed, or used recreationally without medical supervision, they become poisons that attack the body and mind in distinct ways.

Let us first understand the psychological effects, which are often the most dramatic. LSD (lysergic acid diethylamide) is a hallucinogen. In excessive doses, it can trigger terrifying hallucinations, panic attacks, and a condition called "psychosis" — a break from reality where the user cannot distinguish what is real from what is imagined. This can last for hours or, in vulnerable individuals, become a chronic mental illness. Barbiturates, which depress the central nervous system, cause confusion, poor judgment, slurred speech, and memory loss. Chronic abuse can lead to severe depression and suicidal thoughts. Amphetamines, being stimulants, produce the opposite: extreme agitation, paranoia, violent behaviour, and a psychotic state that closely mimics schizophrenia. The user may feel invincible, then crash into deep despair.

The physical toll is equally devastating. Barbiturates, especially when taken with alcohol, can depress breathing to the point of respiratory failure and death — this is a common cause of fatal overdose. Long-term use leads to physical dependence, and sudden withdrawal can cause life-threatening seizures. Amphetamines overstimulate the heart, causing dangerously high blood pressure, irregular heartbeat, heart attacks, and strokes. They also suppress appetite, leading to severe weight loss and malnutrition. LSD does not typically cause fatal overdose, but it can trigger "flashbacks" — spontaneous recurrences of the drug experience weeks or months later — and may worsen pre-existing mental disorders.

Method: Organise by Pharmacological Class, Derive Effects From Mechanism

Rather than listing each drug's effects independently, group by drug class and derive the adverse-effect pattern from the class's core mechanism.

Step 1: LSD — hallucinogen class

Mechanism: alters serotonin signalling in the brain, distorting sensory perception. Derived adverse effects: hallucinations, delusions, and — because the drug can leave lasting changes in perception circuits — flashbacks that recur long after use stops.

Step 2: Barbiturates — CNS depressant class

Mechanism: enhances GABA (inhibitory neurotransmitter) activity, broadly suppressing brain and brainstem activity, including the respiratory control centre. Derived adverse effects: impaired coordination and speech (general CNS suppression), and at high/combined doses, respiratory depression severe enough to cause coma or death — the depressant mechanism directly explains this specific danger.

Step 3: Amphetamines — CNS stimulant class

Mechanism: increases release/blocks reuptake of dopamine and noradrenaline, overstimulating the nervous and cardiovascular systems. Derived adverse effects: insomnia, anxiety, aggression, and paranoia (overstimulated CNS); raised heart rate/blood pressure and cardiovascular strain (overstimulated cardiovascular system). …