From the Guidelines

Buspirone and Venlafaxine (Effexor) can be used together, but caution is advised due to potential interactions.

The evidence does not provide direct information on the interaction between Buspirone and Venlafaxine, but it does mention that augmenting with another SGA (such as bupropion or buspirone) versus augmenting with cognitive therapy showed no difference in response, remission, or depression severity 1.
Low-quality evidence showed no difference in suicidal ideas and behavior or serious adverse events when augmenting with bupropion compared with augmentation with buspirone, but discontinuation due to adverse events was lower with bupropion than with buspirone 1.
Monitoring for increased serotonin levels is recommended when combining Buspirone with Venlafaxine, as both medications can increase serotonin levels, potentially leading to serotonin syndrome.
Dose adjustments may be necessary to minimize the risk of adverse interactions.

When prescribing Buspirone and Venlafaxine together, close monitoring of the patient's condition and adjustment of the treatment plan as needed is crucial.
Regular follow-up appointments should be scheduled to assess the patient's response to the treatment and to monitor for potential adverse interactions.
Patient education on the potential risks and benefits of combining these medications is essential to ensure informed decision-making and to promote adherence to the treatment plan.

From the Research

The potential interactions between Buspirone and Venlafaxine are not directly addressed in the provided studies, but some information can be inferred from the available data 2, 3, 4, 5, 6.
One study compared the efficacy of venlafaxine extended release and buspirone in outpatients with generalized anxiety disorder, and found that venlafaxine XR was significantly more efficacious than buspirone on the HAD anxiety subscale 4.
Another study mentioned that venlafaxine was no more effective than buspirone in one trial, but did not provide further information on potential interactions between the two drugs 3.
There is no direct evidence on the safety of combining buspirone and venlafaxine, but the studies suggest that both drugs can be effective in treating generalized anxiety disorder and depression, with some differences in efficacy and side effect profiles 4, 6.

Buspirone has been shown to be effective in treating generalized anxiety disorder, but its efficacy may be lower compared to venlafaxine extended release 4, 6.
Venlafaxine extended release has been found to be effective in treating generalized anxiety disorder and depression, with a favorable side effect profile 4, 5, 6.
The combination of venlafaxine and other antidepressants, such as mirtazapine, has been shown to be effective in treating treatment-refractory depression, but the safety and efficacy of combining buspirone and venlafaxine are not well established 5.

The choice of buspirone or venlafaxine for treating generalized anxiety disorder or depression should be based on individual patient needs and medical history 3, 4, 6.
Patients with a history of chemical dependency may be more suitable for buspirone, while those with treatment-refractory depression may benefit from the combination of venlafaxine and other antidepressants 5, 6.
Further studies are needed to fully understand the potential interactions between buspirone and venlafaxine, as well as their efficacy and safety in different patient populations 2, 3, 4, 5, 6.