Prozac, also fluoxetine, a selective serotonin reuptake inhibitor (SSRI), is widely prescribed to treat major depression, panic disorder, obsessive-compulsive disorder, and certain other mental or mood conditions. This medication is believed to work by blocking the absorption of serotonin, a neurotransmitter that is associated with important functions like appetite, sleep, and sex drive. By blocking the reuptake of serotonin in the brain, Prozac and fluoxetine increase the amount of active serotonin that can be delivered to neural receptors, potentially leading to improvements in mood, energy levels, appetite, and sleep.
While Prozac (brand name fluoxetine) can be highly effective in treating mental disorders in some people, it is not always safe to use if you are taking certain other medications. Below are a few of the possible drugs to avoid due to interactions. Talk to your doctor about all medications you are currently using or have recently used so that he or she can determine if Prozac is safe for you.
Tamoxifen is often prescribed to treat estrogen receptor-positive breast cancer (the most common type of breast cancer in women). It works by blocking the production of estrogen and stopping or reversing tumor growth. Unfortunately, Prozac can render tamoxifen ineffective by inhibiting the CYP2D6 enzyme. Without CYP2D6, tamoxifen cannot be converted into its active form in the body. This is an important interaction to keep in mind, especially since 20-30% of the women who take tamoxifen are also prescribed antidepressants like Prozac.
Sometimes prescribed to treat bipolar disorder, lithium should not necessarily be taken alongside Prozac. There have been some reported cases of lithium toxicity and serotonin syndrome, a condition that can cause seizures, increased heart rate, extreme blood pressure changes, hallucinations, and other serious side effects.
Benzodiazepines are a class of drugs that include sedatives, anticonvulsants, and muscle relaxants. Prozac and fluoxetine can cause the body to process benzodiazepines more slowly, which can lead to side effects such as excessive drowsiness, confusion, and impaired coordination.
Phenytoin and Carbamazepine
The anticonvulsant drugs phenytoin and carbamazepine are both used to treat epilepsy, and phenytoin is also sometimes prescribed to treat nerve pain or bipolar disorder. There have been reports that when administered alongside Prozac, some patients experience an elevated concentration of the anticonvulsant drug in their plasma, increasing the risk of side effects including nausea, vomiting, dizziness, confusion, and worsening seizures.
Pimozide and Thioridazine
Pimozide and thioridazine are both antipsychotic medications; while pimozide is primarily used to treat the motor and phonic tics caused by Tourette’s syndrome, thioridazine is usually prescribed to treat schizophrenia. Both drugs can have a very serious interaction with Prozac. By inhibiting the CYP2D6 enzyme, Prozac slows down the body’s processing of pimozide or thioridazine, which increases your risk of developing life-threatening arrhythmias (an irregular heartbeat).
Be Safe: Discuss Medications with Your Doctor
The medications listed above are not the only ones that can interact with Prozac and fluoxetine, so it’s incredibly important that you tell your doctor about all the prescription and non-prescription drugs you are currently taking. This will allow your doctor to weigh risk factors against benefits and make an informed decision to keep you safe.