The study consists of measurement of antidepressant-induced excessive sweating and its treatment with an experimental medication, terazosin (approved for hypertension), that will be added to the antidepressant. This study is for people who take an antidepressant due to a depressive disorder. This is an open-label study (no placebo group) that will last 5 weeks, with one week of baseline measurement and four weeks of treatment with the study medication. The study is based on the hypothesis that terazosin will be effective in reducing the severity of excessive sweating caused by antidepressant treatment, and will have minimal side-effects.

Inclusion Criteria:

1. Age 18 - 75 years
2. Clinical diagnosis of a Depressive disorder (Diagnostic and Statistical Manual of Mental Disorders - IV-TR)
3. Presence of excessive sweating by self-report
4. The excessive sweating started after initiation of an antidepressant and, if treatment with the antidepressant was interrupted, did not persist for more than 4 weeks during that interruption
5. Treatment with the antidepressant is deemed to be clinically necessary due to substantial benefit from this antidepressant, and failure to respond to or tolerate an alternative
6. Excessive sweating has persisted for at least 4 weeks prior to baseline assessment
7. The excessive sweating is rated by the patient as at least moderately bothersome.
8. Episodes of excessive sweating occur at least twice a week for last 4 weeks

Exclusion Criteria:

1. Presence of another known disease that could potentially cause excessive sweating
2. Failure to respond to antiadrenergic (reducing activity of the sympathetic nervous system) treatment in the past
3. Blood pressure less than 110 mm Hg systolic at the screening or baseline visits
4. Orthostatic hypotension by history or on assessment at the screening or baseline visits (defined as a decrease of 10 mm Hg or greater after standing for 2 minutes).
5. Current antihypertensive treatment
6. History of significant cardiac disease, including coronary artery disease
7. Current use of phosphodiesterase type 5 inhibitors: sildenafil (ViagraTM), tadalafil (CialisTM), or vardenafil (LevitraTM)
8. History of priapism (persistent and painful erection)