@SidekickSally
Is your DH in regular contact with a psychiatrist or CPN?
The reason I ask is that it's not unheard of for some people's Depression not to respond to the typical anti-depressants that GP's alone can describe, so simply going back and forward to the doctor every time there is a relapse is a pointless, never-ending cycle. It's also the case that some of the more common drugs can cause the absolute worst side-effects in a few people. It's not always just a case of a bit of nausea and a loss of libido.
There are a million and one atypical anti-depressants around now, but they'll only usually be prescribed by a psychiatrist after GP treatment has failed, so if your OP has given up on meds simply because he's been to his GP and that hasn't helped, then he really needs to go back and ask for a referal.
FWIW, I don't medicate myself despite suffering with on/off periods of clinical depression my entire adult life. I had entirely negative experiences with all the typical anti-depressants, fluoxetine, citalopram, etc etc, but the only thing I did find remotely helpful was an anti-convulsant. It didn't lift my depression entirely, but I did notice a mild but very definite sedative effect, which I'd imagine at particular points in my life may have actually been exactly what I required.
If he's unconvinced or doesn't feel able to go through this, it might also help to get in touch with a mental health advocacy service, as they'll be able to talk him through exactly what the process entails, likely options, and perhaps even accompany him to appointments if that's what he desires. A lot of people crave having back-up and support, but don't want family members or spouses in that role, so having an entirely unrelated party to hand can be just what's needed.
Good luck.