SJW is a MAOI - monoamineoxidase inhibitor and can cause a serious interaction with SSRI's.

MAOI's work by blocking the enzyme monoamine oxidase which breaks down the neurotransmitters dopamine, serotonin, and norepinephrine (noradrenaline). MAOIs can be as effective as tricyclic antidepressants, although they can have a higher incidence of dangerous side effects (wikipedia)

Tricyclics block the reuptake of certain neurotransmitters such as norepinephrine (noradrenaline) and serotonin (Wikipedia)

SSRIs are said to work by preventing the reuptake of serotonin (Wikipedia)

So from what I can gather if you took both you would be creating an excess of certain neurotransmitters such as seroton, that couldn't then be broken down. They would essentially have nowhere to go.

Hope this helps,

Love and Hugs,
Tara