Which two drugs cause the most harm Quizlet?

October 10, 2025 •

3 min read

According to a landmark study in The Lancet, when considering overall harm to both the user and to society, alcohol is the most harmful drug, followed by heroin [1.4.2, 1.4.3, 1.6.5]. This article explores the complex answer to 'Which two drugs cause the most harm Quizlet?'.

Quick Summary

Scientific studies consistently rank drugs based on a wide range of harms. While answers vary, alcohol and heroin are identified as the most damaging overall due to their effects on individuals and society.

Key Points

Overall Harm: Scientific studies ranking drug harms consistently place alcohol as the most harmful drug overall when considering damage to both users and wider society [1.4.2, 1.4.3].
Two Categories of Harm: Drug harm is measured in two main ways: direct harm to the user (e.g., overdose, dependence) and harm to others (e.g., crime, economic cost) [1.4.5].
Alcohol's Impact: Alcohol's top ranking is primarily driven by its widespread use and its exceptionally high score in the 'harm to others' category [1.3.7, 1.4.7].
Heroin's Danger: Heroin ranks as one of the most harmful drugs due to its extreme addictiveness and high risk of fatal overdose, making it one of the most dangerous substances to the individual user [1.3.2, 1.4.7].
Context vs. Simplicity: While Quizlet may provide various answers, detailed pharmacological analysis reveals a more complex picture than a simple two-drug answer [1.5.1, 1.5.3].
Fentanyl's Rise: In terms of current overdose deaths, the potent synthetic opioid fentanyl has become a leading cause of harm, often co-used with other drugs [1.5.2, 1.5.4].
Policy Implications: Experts argue that official drug classifications often do not align with the scientific evidence of their actual harm [1.4.2].

The Complexity of Measuring Drug Harm

Defining which drugs cause the most harm is more complex than it appears. Scientists use a multi-criteria decision analysis (MCDA) to rank substances, evaluating them across numerous parameters [1.4.5]. These criteria are broadly divided into two categories: harm to the user and harm to others. A seminal study led by Professor David Nutt and published in The Lancet established a comprehensive framework for this analysis, assessing 20 different drugs [1.4.2, 1.4.7].

Dimensions of Harm

Harm to Users: This includes drug-specific mortality (overdose), long-term damage to physical and mental health, dependence potential, and loss of tangible assets like housing or employment [1.4.5]. For example, heroin and crack cocaine rank highest for harm to the individual user [1.4.7].
Harm to Others: This dimension evaluates the drug's societal impact, including crime, environmental damage, family adversity, economic cost (e.g., healthcare, law enforcement), and even international damage [1.4.2, 1.6.5].

Drug 1: Alcohol

Based on the comprehensive MCDA approach, alcohol is consistently ranked as the most harmful drug overall, primarily due to its staggering impact on others [1.4.3, 1.6.1]. While it may not be the most deadly per use, its widespread legality, social acceptance, and high consumption rates amplify its negative consequences across society [1.6.4, 1.3.7].

Why Alcohol Ranks Highest

Widespread Use: A significant portion of the population consumes alcohol, increasing the overall incidence of harm [1.3.6].
Societal Costs: Alcohol contributes heavily to economic costs through healthcare demands for treating conditions like liver disease and cancer, as well as the costs of crime and law enforcement related to public intoxication and drunk driving [1.2.4, 1.3.7].
Harm to Others: Alcohol scored the highest by a wide margin in the 'harm to others' category, which includes its role in assaults, domestic violence, and traffic accidents [1.4.3, 1.4.7]. The World Health Organization (WHO) states that no level of alcohol consumption is safe for health [1.5.1].

Drug 2: Heroin

Heroin consistently ranks as one of the most harmful drugs, typically second or third overall but often first when considering direct harm to the user [1.4.7, 1.3.2]. It is a powerful opioid with a very high potential for causing dependence and death.

The Dangers of Heroin

High Dependence: Heroin is notoriously addictive. Its use can quickly lead to physical and psychological dependence, where users need the drug to feel normal and avoid severe withdrawal symptoms [1.3.6].
Overdose Risk: As an opioid, heroin can cause respiratory depression, where breathing slows or stops, leading to fatal overdose. This risk is a primary contributor to its high harm score [1.3.8].
Economic and Social Impact: Heroin use is linked to significant economic costs and crime as individuals may resort to illegal activities to fund their addiction [1.3.7]. The rise in prescription opioid abuse has also been linked to an increase in heroin addiction, as it can be a cheaper alternative [1.3.6].

It is worth noting that in recent years, the synthetic opioid fentanyl has surpassed heroin in many areas as the primary driver of opioid-related deaths due to its extreme potency [1.5.2, 1.5.4]. While heroin is a classic example in harm-ranking studies, fentanyl represents the evolution of the opioid crisis.

Comparison Table: Alcohol vs. Heroin


Feature	Alcohol	Heroin
Overall Harm Score (Nutt et al.)	72 [1.4.3]	55 [1.4.3]
Primary Harm Category	Harm to Others [1.4.7]	Harm to User [1.4.7]
Legal Status	Legal (with age restrictions) [1.3.7]	Illegal (Class A / Schedule I) [1.3.8]
Dependence Potential	High [1.2.4]	Very High [1.3.2, 1.3.6]
Primary Health Risks	Liver disease, cancer, heart disease, accidents [1.2.4]	Overdose, respiratory failure, infectious diseases (from injection) [1.3.8]
Societal Impact	High economic cost, crime, family adversity [1.3.7]	High rates of crime, healthcare burden [1.3.7]

Conclusion

While study materials on platforms like Quizlet may offer simplified answers, such as 'alcohol and tobacco' or 'cocaine and alcohol', the most robust scientific evidence points to a nuanced conclusion [1.5.1, 1.5.3]. Based on a comprehensive evaluation of 16 different harm criteria, alcohol and heroin emerge as the two substances causing the most overall damage. Alcohol's harm is driven by its widespread use and societal impact, while heroin's is characterized by its severe addictiveness and direct danger to the user. Understanding this distinction is critical for developing effective public health policies and addiction treatment strategies.

For anyone struggling with substance use, help is available. The Substance Abuse and Mental Health Services Administration (SAMHSA) offers a National Helpline. https://www.samhsa.gov/find-help/national-helpline

Frequently Asked Questions

According to a comprehensive study published in The Lancet, alcohol and heroin are the two drugs that cause the most harm overall when combining their effects on users and on society [1.4.2, 1.4.3].

Alcohol is ranked as more harmful overall because its widespread use leads to a much greater total societal impact, including crime, economic costs, and family adversity. While heroin is more harmful to the individual user, alcohol's 'harm to others' score is significantly higher [1.4.3, 1.6.1].

Studies show that heroin, crack cocaine, and methamphetamine are the most harmful drugs to the individual user, based on factors like dependence, mortality, and physical damage [1.4.7].

Fentanyl is a synthetic opioid that is significantly more potent than heroin, making the risk of a fatal overdose extremely high. In recent years, it has become a primary driver of drug overdose deaths, often more so than heroin [1.5.2, 1.5.4].

Yes, in many studies, the legal drugs alcohol and tobacco are ranked among the most harmful substances, often surpassing many illegal drugs like ecstasy or LSD in overall harm scores [1.3.2, 1.4.2].

It refers to the negative impacts a drug has on society, beyond the user. This includes factors like the drug's role in crime, the economic cost of healthcare and law enforcement, damage to family units, and environmental harm [1.4.2, 1.6.5].

Different sources may use different criteria. Some might focus only on overdose deaths, while others, like the study by Professor David Nutt, use a more comprehensive model that includes 16 factors of harm to both the user and society, leading to different but more nuanced rankings [1.4.5, 1.4.2].