Opioids are a class of drugs that act on opioid receptors in the brain and nervous system to relieve pain, but they also affect mood, breathing, and digestion.

What they’re used for
• Medical pain relief: after surgery, injury, cancer pain, severe chronic pain
• Cough suppression & diarrhea control: some opioids are used in low doses for these

How they work

Opioids bind to opioid receptors (mainly mu, kappa, and delta receptors). This:
• Reduces how strongly the brain perceives pain
• Creates feelings of relaxation or euphoria
• Slows breathing and heart rate
• Can cause drowsiness and constipation

Common examples
• Natural opioids: Morphine, Codeine (from the opium poppy)
• Semi-synthetic opioids: Heroin, Oxycodone, Hydrocodone
• Synthetic opioids: Fentanyl, Methadone, Tramadol

Effects

Short-term effects
• Pain relief
• Euphoria or calm
• Drowsiness
• Nausea, itching, constipation

Long-term or high-dose risks
• Tolerance (needing more for the same effect)
• Dependence and addiction
• Respiratory depression (slow or stopped breathing)
• High risk of overdose, especially when mixed with alcohol or sedatives

Withdrawal symptoms

When someone dependent stops using opioids, they may experience:
• Muscle aches
• Sweating, chills
• Anxiety, insomnia
• Nausea, diarrhea
(Withdrawal is rarely fatal but very uncomfortable.)

Safety notes
• Opioids should only be used as prescribed
• Mixing with alcohol or benzodiazepines is especially dangerous
• Naloxone can reverse opioid overdoses and save lives