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What Drugs Most Negatively Affect Mental Health?

Drug addiction and mental illness go hand-in-hand. Compared to the general population, those with a substance use disorder are twice as likely to have mood and anxiety disorders, with the opposite also true. However, while substance abuse co-occurs with mental illnesses, it’s unclear whether one helps cause the other or if common underlying risks affect both disorders. Still, when looking at what drugs most negatively affect mental health, these take the price. 

1. Cocaine

Long-term effects of cocaine use can alter the brain reward system and make it less sensitive to natural reinforcements. Some studies suggest cocaine misuse can lead to impaired cognitive function, such as sustaining attention, making decisions, memory, and even performing motor tasks. The use of cocaine, particularly crack, is associated with more frequent and intense psychiatric symptoms like paranoia. 

2. Inhalants

Although rare, long-term use of inhalants can cause delirium and confusion. Not to mention, it’s often the starting point for developing a substance use disorder in the future. Inhalants can cause severe damage the central nervous system that can lead to many impaired functions of the brain and body. Long-term inhalant abusers have a high prevalence of anxiety disorders, panic disorders, and elevated suicide rates compared to the general population. Estimates also say almost 45% of inhalant users developed a personality disorder. 

3. Ketamine

Ketamine is used for anesthesia and pain relief, but people also use it illegally for its hallucinogenic effect. Long-term use of the drug can alter people’s perception of reality, making them feel detached from their bodies. Regular uses can have mood and personality disorders such as bipolar disorder, psychosis, and problems with concentration. Interestingly, Ketamine is now being used for depression treatment in some cases. 

4. Kratom

Kratom is a tree that has compounds that can have mind-altering effects. It has responses similar to opioids and other stimulants. Some people experience symptoms of psychosis that can become permanent after long-term use. Although rare, some users can become addicted to kratom. 

5. LSD

Long-term effects of hallucinogens like LSD can leave residual psychological and cognitive impact; but, these effects are still poorly understood. Overall, two long-term effects are persistent psychosis and hallucinogen persisting perception disorder (HPPD). Sometimes, both conditions even occur together, alongside substance use disorders and other mental health issues. 

6. Marijuana

Overall, several studies have linked marijuana use to increased risk for psychiatric disorders, including schizophrenia, depression, anxiety, and substance use disorders, to name a few. However, there’s little evidence to explain to what extent marijuana can trigger these conditions. The amount of drug, the length of misuse, age, and even genetic vulnerability plays a role. After adjusting for various confounding factors in some new studies, no association between marijuana use and mood and anxiety disorders was found.


MDMA is one of those drugs that directly affects the brain by increasing the activity of various neurotransmitters. High doses of MDMA causes mood-elevating effects. However, when this happens, there’s a surge of serotonin that can cause negative psychological after-effects. The problem of long-term use of MDMA is that it depletes the body of serotonin levels and causes anxiety, paranoia, depression, and impairment of attention processes and memory. 

8. Methamphetamine

People who use methamphetamine long term may exhibit symptoms that can include significant anxiety, confusion, insomnia, mood swings, and violent behavior. It is also common for them to struggle with psychotic features, including paranoia, visual and auditory hallucinations, and delusions. These mental disorder symptoms can sometimes last for months or years after a person has quit using methamphetamine.

9. PCP

While the long-term use of most dissociative drugs has not been investigated systematically, research shows persistent speech difficulties, memory loss, depression, suicidal thoughts, anxiety, and social withdrawal. Even in the short-term, people who take high doses of PCP can struggle with hallucinations, extreme panic, and anxiety. 

10. Prescription Drugs

Prescription stimulants are medicines generally used to treat attention-deficit hyperactivity disorder (ADHD) and narcolepsy. When people overdose and overly abuse prescription drugs, they can also struggle with confusion, aggression, hallucinations, and panic states.

11. Steroids

Steroids and appearance and performance-enhancing drugs (APIs) can cause short-term and long-term effects on mental health and overall health. Chronic use of anabolic steroids can also cause dysfunction of these reward pathways in animals. People can struggle with substance abuse and a reduction in reward-related actions. 

Finding Help for Addiction

If you or a loved one is struggling with addiction, please know there are treatment options available. At Lighthouse Recovery Institute, our dual diagnosis programs can help those with substance use disorders that experience co-occurring mental health problems. When it comes to assessing the drugs that most negatively affect mental health, our addiction specialists know how to react to create a personalized treatment plan. Recovery is possible with the right course of treatment, support, and a team of specialists by your side. Start your recovery journey today.

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