When Medications and Substances Mimic Mental Illness

The field of psychiatry is changing.

More and more, I am seeing mental health symptoms that are caused by substances, rather than illnesses that develop on their own. These substances can be illegal drugs, like marijuana or synthetic drugs — but they can also be prescription medications, including ones prescribed by psychiatrists.

This raises a hard question:
Are some of the symptoms I’m seeing preventable?
And even harder: Are some people being harmed by the very treatments meant to help them?

One important thing to understand about psychiatry is this: any medication that changes the mind also has the power to change it in unwanted ways. Even medications prescribed with good intentions can sometimes cause new mental health symptoms.

This is why informed consent matters. Patients deserve to know not just what a medication might help with — but also what it might cause.

If you ever develop new or worsening symptoms and end up in a doctor’s office or emergency room, one key question should never be ignored:
Could this be related to a medication or substance?

Here are a few examples.

As marijuana has become easier to access — and much stronger — we are seeing more people come to the hospital with psychosis. Synthetic marijuana, in particular, has sent many people to the emergency room with severe psychiatric symptoms. These situations can be confusing. It can be difficult to tell the difference between a mental illness and a reaction to a substance, especially if the substance has been used repeatedly over time.

Something similar is happening with stimulant medications used for ADHD. As prescriptions have increased, there has also been an increase in emergency visits for mania and psychosis. In some cases, these reactions are later labeled as bipolar disorder or schizophrenia, even though they may have been caused by the medication itself.

Antidepressants are another example. These medications carry a warning about an increased risk of suicidal thoughts and behaviors, especially when starting the medication or changing the dose. Some patients describe these thoughts as feeling very different from anything they experienced before — more intrusive, more intense, and harder to control. These reactions are often linked to a side effect called akathisia, which feels like unbearable inner restlessness, both mentally and physically. People may act in ways that feel out of character, which can look like a sudden personality change.

Medication changes can also cause problems when they happen too quickly. Rapid dose changes or switching from one drug to another can overwhelm the brain. Withdrawal symptoms are often missed or misunderstood. The brain adapts to medications over time, and sudden changes can cause symptoms that look like anxiety, depression, psychosis, mania, panic, or severe insomnia — often worse than anything the person experienced before treatment.

Too often, these reactions are mistaken for a relapse or “treatment resistance,” leading to even more medication, rather than stepping back and asking whether the medication itself could be the cause.

There is much more to say about this, but my goal here is simple: to help people pause and think differently. A large number of the symptoms I see appear to be drug-induced, not signs of a permanent mental illness.

Because I can’t be in every exam room, here are a few important points to remember:

• A substance-induced condition does not automatically mean lifelong medication or a permanent diagnosis. If that is being suggested, it is reasonable to seek another opinion.

• Withdrawal can happen even while someone is still taking medication, especially if doses are changed quickly or medications are swapped.

• Medications can cause symptoms that look exactly like psychiatric disorders and should always be considered as a possible cause.

• Marijuana may feel safe because it is legal and widely accepted, but increased use has been linked to more psychiatric problems. This risk deserves honest discussion.

Questioning these issues does not mean rejecting mental health care. It means becoming an informed participant — asking questions, understanding risks, and making decisions that respect how sensitive the brain really is.

Dr. Marissa Witt-Doerring is a board-certified psychiatrist and co-founder of TaperClinic, specializing in psychiatric withdrawal and safe, individualized tapering.

Di Forti, M et al. (2019). The contribution of cannabis use to variation in the incidence of psychotic disorder across Europe (EU-GEI): A multicentre case-control study. The Lancet Psychiatry, 6(5), 427–436.

Moran, LV et al. (2019). Psychosis with methylphenidate or amphetamine in patients with ADHD. The New England Journal of Medicine, 380(12), 1128–1138.

U.S. Food and Drug Administration. (2004). Suicidality in children and adolescents being treated with antidepressant medications.

Horowitz, M. A., & Taylor, D. (2019). Tapering of SSRI treatment to mitigate withdrawal symptoms. The Lancet Psychiatry, 6(6), 538–546.

Fava, GA et al. (2015). Withdrawal symptoms after selective serotonin reuptake inhibitor discontinuation: A systematic review. Psychotherapy and Psychosomatics, 84(2), 72–81.