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Chapter 19: Medicines & Drugs
Lesson 1 — What Are Medicines?
Medicines are chemical substances used to treat, prevent, or diagnose illness. They are carefully tested for safety and effectiveness before being approved.
Prescription (Rx)Requires a doctor's order; used for serious/complex conditions; regulated dosing
Over-the-Counter (OTC)Available without prescription; safe when used as directed on label
VaccinesStimulate immune response to provide immunity without causing disease
Side EffectsUnintended effects of a medicine; listed on labels; some require medical attention
Safe Medicine Use
Always follow dosing instructions, check expiration dates, and never share prescription medications. Drug interactions can be dangerous — tell your provider all the medications you take.
Always follow dosing instructions, check expiration dates, and never share prescription medications. Drug interactions can be dangerous — tell your provider all the medications you take.
Quick Check: What is the difference between prescription and OTC medications?
Lesson 2 — Drug Misuse & Abuse
Drug misuse means using medication in a way other than intended — wrong dose, wrong person, or wrong purpose. Drug abuse is intentional use to alter mood or perception.
- Tolerance — needing more of a drug to get the same effect
- Dependence — body adapts and requires drug to function normally
- Addiction — compulsive use despite harmful consequences; a chronic brain disorder
- Withdrawal — physical/psychological symptoms when stopping a substance
Quick Check: What is the difference between drug tolerance and drug dependence?
Lesson 3 — Types of Drugs & Their Effects
Psychoactive drugs alter brain chemistry and behavior. They are categorized by how they affect the central nervous system:
StimulantsSpeed up CNS; increase alertness (caffeine, amphetamines, cocaine)
DepressantsSlow CNS; reduce anxiety (alcohol, benzodiazepines, barbiturates)
OpioidsBlock pain receptors; high addiction potential (morphine, oxycodone, heroin)
HallucinogensDistort perception of reality (LSD, psilocybin, PCP)
Quick Check: How do stimulants affect the central nervous system differently than depressants?
Lesson 4 — Prevention & Getting Help
Understanding risk factors, building refusal skills, and knowing where to get help are essential life skills for navigating a world where drugs are present.
- Risk factors: peer pressure, stress, family history of addiction, trauma
- Protective factors: strong relationships, school engagement, healthy coping skills
- Practice refusal scripts: "No thanks, it's not for me" — short, confident, no explanation needed
- SAMHSA National Helpline: 1-800-662-4357 (free, confidential, 24/7)
Quick Check: Name two risk factors and two protective factors for drug misuse.
Chapter Vocabulary
MedicineA chemical substance used to treat, prevent, or diagnose illness.
Prescription drugA medication that requires a doctor's written order before it can be dispensed.
Drug misuseUsing a medication in a manner other than intended (wrong dose, person, or purpose).
Drug abuseIntentional use of a substance to alter mood or perception in a harmful way.
ToleranceThe need for increasing amounts of a drug to achieve the same effect.
DependenceA physical or psychological need for a substance to function normally.
AddictionA chronic brain disorder involving compulsive drug use despite harmful consequences.
StimulantA drug that speeds up central nervous system activity.
DepressantA drug that slows central nervous system activity.
OpioidA class of drugs that block pain receptors and carry high addiction potential.