A PubMed search turns up a little on St. John's wort and its potential for use in treating some pain syndromes. Not much in terms of clinical evidence in humans.

If a physician treating arthritis feels there might be benefit in prescribing an antidepressant, it would be worthwhile asking about SJW as an alternative to tricyclics. SJW use is associated with fewer side effects, though it can also interact with other medications.

i went into herbal medicines looking for antidepressants, and have found quite a few. the ones that work best for me have been skullcap, lemon balm, and lavender. i can grow skullcap and lemon balm organically at home, and i am always trying to get a good stand of lavender. i dry the skullcap, use skullcap and lemon balm leaves fresh during their seasons, and tincture skullcap and lemon balm in brandy. i keep essential oil of lavender ready for depression and headaches, one drop rubbed on the forehead and wrist points. if i ever get enough lavender to harvest, i will tincture the leaves, and dry the flowers and leaves for tea.
i took pharmaceuticals for years, and herbs do as good a job for me, and have few-to-no side effects. they are definitely worth trying, and have the added benefit of being quite inexpensive. and, if it is important, your use of them does not show up on medical records.

St. John's Wort is not a good herb in my opinion. It can cause depression, particularly when taken on a long-term basis. St. John's Wort also causes a person to be extremely sun sensitive. That means a person can easily become sun burned from little exposure to the sun.

I've been trying Borage oil for a few weeks instead of the med prescribed to me by my rheumatologist.

I seem to be able to wake up more fully daytimes, but I am not certain if the arthritis deterrance is as effective or not. It does provide me with an alternative to take to decrease my tolerance to the prescribed one, though, so I won't have to take ever-increasing doses.

If your arthritis is auto-immune (rheumatoid) be careful of herbs that affect B-leukocytes, as these herbs will only increase inflammation. However, siberian ginseng (eleutherococcus sinensis), which falls in that class, helps with muscle & mental fatigue and can be cautiously tried to see if it has any greater benefit than side-effect. Secondary caution, take last dose of siberian ginseng before 3 p.m. as it can cause sleeplessness or delayed onset of sleep if taken too late in the day. Sometimes it's a trade off...

I usually don't take Ginseng, because of the blood pressue effect. I occasionally take a cup of the "ginseng for females"' (Dong Qui?) but am uncertain of the effect.

The B-leukocyte effect is interesting; I will have to do some research on that.

Lotus Flowers. I drink the tea all throughout the day. Its wonderful! Doctors have this new idea that antidepressants can help with pain issues and that severe pain will obviously effect your mood over time, probably because you're always in pain and thats not a fun life. Even though their thoughts may seem a little far fetched at times. There is scientific backing to this one. Antidepressants help rebalance your serotonin receptors (serotonin is one of the chemicals our brain sends out to our body to tell us we feel good) so antidepressants tell your brain and body that you feel good. Taking a prescribed antidepressant may work for some. One of the major problems is with all antidepressants it takes at least 2weeks of taking it everyday for it to build up in your blood enough, just to see if it even works for u. Then if u decide it doesn't (side effects too bad,or no improvement) once u stop taking it it takes another 2weeks to get out of your blood. So, those 4weeks can be really bad. And everyone is different. Some of the side effects are worse then severe pain and depression, like suicide. Not good.
I have found that taking Lotus flower tea is all I need. Nothing has to build up in your blood for u to feel it. The effects are instant and there are no side effects.
And theres a great pain relieving property to it. Theres a lot of scientific info. on it at thelawofnature.com and if you send them an email they'll mail u a free sample of Lotus flower.
Honestly I am thankful everyday that I found lotus, it makes it so I can live my life.
Write back anytime. Best wishes.