SSRIs are notoriously NOT safe. In younger people, they often increase suicidal ideation. Even in adults, there is a very dangerous period when you first start taking them where suddenly you have more energy, but you are still massively depressed. People die because before they were so depressed they couldn't even take action to suicide, and the drugs give them just enough of a lift that they can.

Apart from that, there's the massive list of side-effects, many of them extremely common.

Complete loss of libido, erectile dysfunction, or worse, your libido is unchanged but you completely lose the ability to orgasm.

Insomnia, cause that's what a depressed person needs, even less sleep and more time for rumination in bed.

Akathisia, which is an uncontrollable need to move your body, think restless leg syndrome but it's your entire body. You literally cannot sit still.

Less life-destroying but still very obnoxious: increased sweating, dry mouth (which can ruin your teeth if you don't manage it with biotene or gum or something), blurred vision, headaches, the list goes on.

This is without even mentioning the risk of serotonin syndrome yet, which can straight up literally kill you if you don't make it to a hospital. It happens when your serotonin level is too high, and can cause seizures, fever, arrhythmia, or death.