Brief Answer:
observe for below mentioned symptoms, even though less likely to occur

Detailed Answer:
Hi

I have gone through your query.

Using trazodone together with venlafaxine can increase the risk of a rare but serious condition called the serotonin syndrome, which may include symptoms such as confusion, hallucination, seizure, extreme changes in blood pressure, increased heart rate, fever, excessive sweating, shivering or shaking, blurred vision, muscle spasm or stiffness, tremor, incoordination, stomach cramp, nausea, vomiting, and diarrhea.

Even though it is less likely to occur but I have mentioned here the symptoms, so that you can just observe yourself. I also would suggest you not to take any medication if you are not aware of the purpose for which it is used.
You should seek immediate medical attention if you experience these symptoms while taking the medications.

Hope this helps.
Take care.

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