Can Appetite Suppressants Cause Depression?

January 9, 2024 |

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Yes, appetite suppressants do carry the potential to cause depression.

Let me guess; you might be feeling down lately because of the new appetite suppressant you have been using for a while now, or you might even have discontinued the prescription.

Nonetheless, you asked the right question because your daily blues indicate depression caused by anorexiants.

Appetite suppressants mess with your neurotransmitters to keep off those hunger pangs. So, a disturbance in the central nervous system caused by these drugs may serve as a biochemical basis for the incidence of depression in the users.

In this article, I will provide you with science-backed and factual answers to your every question regarding the relationship between appetite and depression.

You will find out how appetite suppressants affect depression and vice versa and also if it is safe to take anti-depressants with appetite suppressants.

So, keep reading to find out the details.

Appetite Suppressants and Depression

For this section, I have skimmed through various clinical trials, reviews, and different research papers to provide you with an insight into the scientific evidence that exposes the link between appetite suppressants and depression.

I’ll start this section with this 2012 review article which has discussed the relationship between various drugs and depressive illness.

One section of this review discusses appetite suppressants.

And according to it, people who are aged or are genetically predisposed to depression or pre-diagnosed with it are more susceptible to developing drug-induced depressive illness.

This review fetched various clinical trials performed on anorexiants like phentermine, phenmetrazine, Louria, diethylpropion, and fenfluramine which revealed their potential to cause depression, especially as a withdrawal symptom in the participants of the studies.

Withdrawal of phenmetrazine and Louria was found to cause severe depression in the subjects and made them suicidal.

In one of the studies included in the review, scientists prescribed diethylpropion to the patients, and 4.2% of them reported an incidence of depression because of it.

According to another study included in this review, both fenfluramine and phentermine produce some symptoms of depression in the patients.

However, the fenfluramine carries a higher risk of causing the disease in users than the phentermine.

This review article discussed the two kinds of appetite suppressants that work either via catecholamine or serotonin pathways.

(Both catecholamines and serotonin are neurotransmitters in the brain that play a role in suppressing appetite. Examples of catecholamines are adrenaline, noradrenaline, and dopamine.)

According to the review, fenfluramine is an anorectic drug that works to suppress appetite via the serotonin pathway. It may cause severe depression if it is stopped abruptly, and thus it is recommended to reduce it gradually.

Moreover, this review stated that catecholamine-mediated drugs like amfepramone, phentermine, and mazindol are the preferred treatment choice for obesity in patients with a history of depression as they don’t aggravate their symptoms.

Hence proved that appetite suppressants hold the potential to cause depression.

Long-term effects of phentermine on the brain?

Since phentermine is a psychostimulant and a sympathomimetic amine, it can cross the blood-brain barrier and induce changes in the brain’s neurotransmitters and the central nervous system to impart the desired appetite suppressing effect on the consumer.

And thus, you may suspect it to leave some long-term effects on the brain.

In fact, there are case reports that prove that phentermine may produce some effect on the brain either on its own or in combination with other drugs.

This 2018 case report may serve as evidence of phentermine brain damage.

According to it, a woman suffered from recurrent ischemic stroke or intracerebral hemorrhage whenever she took phentermine.

This case report has documented the second time this 63-year-old woman suffered from ischemic stroke and the first time she had suffered from it was 20 years before, and the reason was the same, phentermine.

There are multiple reports of phentermine-induced psychosis in patients when consumed either alone or in combination with other drugs, which hints that phentermine brain fog might be a thing.

This recent 2019 case report is one of the many pieces of evidence that prove that taking phentermine may induce psychosis in consumers. According to it, a 25-year-old woman had recurrent psychosis whenever she took phentermine, and the symptoms subsided whenever she discontinued its use.

This 2011 publication includes four case reports that documented the occurrence of psychosis and mood symptoms in patients taking phentermine, which indicates that it affects the brain.

In the first case report, a woman with a history of bipolar disorder was presented with relapses in symptoms of maniac psychosis characterized by hallucinations, argumentative behavior, and pressured speech.

Depression was also reported in her that was characterized by a poor self-image.

The symptoms resolved after discontinuation of phentermine.

In the second case report, a woman with a family history of affective illness had developed paranoid delusions within one week of taking phentermine.

However, she herself was never diagnosed with any psychotic illness before. And although her symptoms abated after discontinuing phentermine, she reported that a schizophrenia type of illness was uncovered in her afterward, for which she had to take treatment for five years.

In the third case report, a man with no prior psychiatric history reported that he suffered from auditory hallucinations and delusion within two weeks of self-medicating himself with phentermine. His symptoms started to subside after discontinuing phentermine, but he continued to report symptoms of depression even after four years.

Again, in the fourth case report, a woman with a history of post-natal depression reported that she suffered from delusion and auditory hallucinations within six days of taking phentermine for recreational purposes.

Therefore, we can conclude that the use of phentermine, the most commonly used appetite suppressant, can lead to some highly undesirable harmful effects on the human brain.

How does depression affect appetite?

All of us manifest different signs of depression in one way or the other. On the one hand, some of you might feel a greater urge to munch on food when you feel blue.

And on the contrary, many others among you might suffer from a loss of appetite when you are feeling down. This is why neuroscientists were compelled to explore how depression alters our food cues.

So, keep reading to understand how depression affects appetite.

According to a study conducted in 2016, different regions of the brain that respond to food stimuli show altered activity during the depression as compared to healthy individuals.

In simpler terms, individuals with a greater appetite during depression showed a greater response to food stimuli. In contrast, individuals with a decreased appetite showed a decrease in the activation of the brain regions involved in perceiving these food cues.

Moreover, certain aberrations in your homeostatic signaling pathways may also alter your brain’s response to food cues during the depression.

In simpler words, your cortisol levels (stress hormone), genetics, metabolic differences, and inflammation inside the body will translate into either an increase or a decrease in your eating behavior during the depression.

Although more research is required to conclude a clear link between appetite and depression but preliminary studies like this one found that participants who have a decreased appetite during the depression had greater cortisol levels which are inversely related to the brain’s response to food cues; thus they ate less.

In contrast, participants who had an increased appetite during the depression had an immunometabolic dysregulation.

This implies that they had a greater inflammation in their body, and the magnitude of their insulin resistance correlated positively with the brain’s response to food cues; thus, they ate more.

Can you take appetite suppressants with anti-depressants?

No, you should not take appetite suppressants with anti-depressants.

According to the Cleveland Clinic, appetite suppressants may interact with medications such as anti-depressants and bring undesirable effects.

Moreover, a case report documented the occurrence of psychosis in a 40-year-old Hispanic woman who was taking a combination of an anti-depressant, namely venlafaxine, with appetite suppressants, namely phentermine/topiramate.

The patient, in this case, reported having developed psychosis within one week of taking this drug combination and was presented with symptoms like delusional thinking and self-injurious behavior.

Moreover, she reported improvement in her symptoms after she discontinued this drug combination and was put on another drug, lurasidone.

Why does appetite decrease with depression?

As I mentioned in one of the headings above, depression alters your brain’s response to food stimuli. There is a decrease in the responsiveness of the different brain regions to food cues in individuals who observe a decrease in their appetite during the depression.

Moreover, they might also have distinct underlying endocrine, immunologic and metabolic states that alter their neurological response to food cues.


To conclude, since appetite suppressants mess with your brain and central nervous system, you may suspect them of triggering mental diseases.

There are many case reports that I have included in the body of this article that indicate conditions like ischemic stroke, psychosis, and severe depression that occurred in individuals taking appetite suppressants. So, it is imperative that you monitor your symptoms when on prescription.

In most case reports, the adverse effect on the brain was observed within one to two weeks of consuming phentermine.

So, look out for symptoms like headaches, dizziness, delusions, hallucinations, suicidal thoughts, etc., and immediately report to your doctor.

Moreover, discuss the medications and psychotic drugs that you are already taking with your bariatrician so that he or she can look for possible drug interactions.

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