My teen was persribed zoloft (sertraline) (50mg) for ocd by gp. is it safe to stay on valerian (200) hops (100) and passionflower (100) as persribed by homeopath?

V. Risky: These three homeopathic meds you mention are all hypnotic and sedating, they also work on serotonin and may interact with zoloft (sertraline) leading to the well known serotonin syndrome which can be very serious. It is always "not a good idea" to have two professionals prescribe for the same problem ( with rare exceptions) . So wold suggest that you discuss all this with your prescribing physician.

Not homeopathic : Neither valerian, hops, or passionflower are homeopathic -- they're herbal medicines given in material quantity, and sedating to boot. Interactions can happen that wouldn't happen with truly homeopathic remedies. Valerian can also interfere with certain liver enzymes that process zoloft; the others are not known to do this. None of these herbals is known to specifically help ocd. Zoloft (sertraline) is.