First of all, do you take any other depression drugs, or mood disorder drugs such as
SNRIs and SSRI ?
If mixed with these, Zoloft can cause serotonin syndrome. This includes fever, sweating, muscle stiffness, trouble thinking clearly, a change in mental functioning, sleepiness, or change in your breathing, heartbeat and blood pressure disorder.
If this is the case, you should stop taking Zoloft and speak to your Doctor.