From the Guidelines
Phentermine can potentially cause hallucinations as a rare but serious side effect, and if you experience hallucinations while taking phentermine, you should stop the medication and seek immediate medical attention. Phentermine is a stimulant medication primarily prescribed for short-term weight loss in combination with diet and exercise, typically at doses of 15-37.5 mg once daily in the morning 1. Hallucinations occur because phentermine affects neurotransmitters in the brain, particularly norepinephrine, which can disrupt normal brain function at higher levels or in sensitive individuals. Other serious neurological or psychiatric side effects that may accompany hallucinations include severe anxiety, paranoia, confusion, or agitation.
Some key points to consider when taking phentermine include:
- The recommended dosage is to be taken once daily up to 37.5 mg, preferably earlier in the day to minimize risk of insomnia 1
- Phentermine should not be used with monoamine oxidase inhibitors or other sympathomimetic amines 1
- Patients who have anxiety or insomnia might feel their condition is exacerbated by phentermine, and would not be ideal candidates 1
- People with a history of psychiatric disorders, those taking other medications that affect brain chemistry (like antidepressants or other stimulants), or individuals using higher than prescribed doses face increased risk of experiencing these effects 1
It is essential to note that while phentermine can be effective for weight loss, its use should be carefully monitored, and patients should be aware of the potential risks and side effects. Never adjust your dosage without medical supervision, and always disclose your complete medical history and medication list to your doctor before starting phentermine 1.
From the FDA Drug Label
Manifestations of acute overdosage include restlessness, tremor, hyperreflexia, rapid respiration, confusion, assaultiveness, hallucinations, and panic states. Manifestations of chronic intoxication with anorectic drugs include severe dermatoses, marked insomnia, irritability, hyperactivity and personality changes. The most severe manifestation of chronic intoxications is psychosis, often clinically indistinguishable from schizophrenia.
Phentermine can cause hallucinations as a manifestation of acute overdosage, and psychosis as a manifestation of chronic intoxication 2 2.
- Hallucinations are a possible side effect of phentermine overdosage.
- Psychosis is a severe manifestation of chronic phentermine intoxication.
From the Research
Phentermine and Hallucinations
- Phentermine, a sympathomimetic amine, has been reported to induce psychosis, including hallucinations, in some individuals 3, 4.
- The exact mechanism of phentermine causing psychosis is still unclear, but it is thought to be related to its ability to increase brain dopamine levels 4.
- Studies have shown that psychotic symptoms, including hallucinations, can develop after taking phentermine, and these symptoms can be resolved once the medication is stopped 3, 4.
- However, some cases have reported repeated psychotic episodes, resulting in chronic occupational and social impairment, highlighting the need for cautious use and monitoring of phentermine 3.
Treatment of Hallucinations
- Cognitive behavioral therapy (CBT) has been shown to be effective in managing positive and negative symptoms of schizophrenia, including hallucinations 5, 6, 7.
- CBT techniques, such as those used in high-yield cognitive behavioral techniques for psychosis (HYCBt-p), can be delivered by case managers and have been shown to improve overall symptom burden, depression, and negative symptoms, with a weak effect on dimensions of hallucinations 6.
- The use of CBT in the treatment of schizophrenia has been recommended by most clinical guidelines, and it is considered a useful intervention for managing psychotic symptoms, including hallucinations 5, 7.