Probably less painful than the toe is right now. Swelling and fluid that builds up inside the joint can cause a tremendous amount of pain. Pressure on the local nerves and blood vessels can cause a throbbing, aching toe.
Many patients like yourself feel desperate for relief from the pain and discomfort. Draining the fluid seems like a good idea until you have time to think about it. But the physician uses a numbing agent such as lidocaine. Lidocaine is a novacaine derivative.
Even before the doctor starts moving the painful toe to find the joint, an injection of this local anesthetic is given. Once the toe is numb, the procedure can be done with no further discomfort to the patient. Usually, pain relief occurs once the fluid is drained. You may have a day or two of residual tenderness or soreness.