The more time a patient spends in a depressed state, the higher is the risk of suicidal acts over time.
Thus, reducing the severity and the duration of a depressed state by antidepressant treatment is likely to be an effective preventive measure for suicidal acts.
However, some randomized clinical trials have shown that adults treated with SSRI antidepressants have risk of either non-fatal self harm or suicidal thoughts than those on placebo.
During one large study have been found that some people who have been taking SSRI and have suicidal tendency, are the ones with specific variations in two genes (depending on the particular mix inherited, these versions increased the likelihood of such thoughts from 2- to15-fold).

Very often patients who are actually bipolar, are misdiagnosed as having major depression, cause there can be only dominant symptoms of depression and mild symptoms of mania (which can go unrecognized) or no symptoms of mania at all.
Other scenario, that is associated with high suicidal risk is having mixed bipolar episodes.
Mixed episode, means having symptoms of mania and depression together, including agitation, trouble sleeping, significant change in appetite, psychosis, and suicidal thinking.
When left untreated this disease tends to get worse overtime, with more frequent and more severe ups and downs.

Do you take some other medicines?