If you have not taken all these 3 drugs, you can not be tested positive by any mean. But if you have taken valerian root you can be positive for Valium or xanax. Because Valium and xanax are benzodiazepene derivative and valerian is natural source of benzodiazepene. You can not be positive for Valium if you have taken st. John's wart as it contains hypericum.
Ok, here is the truth. Xanax (alprazolam) shows up positive as a benzodiazepene class of drug in urine tests. Benzos work by binding to gaba neurotransmitter receptors in the synapse between nerve endings in the brain. Gaba is mainly responsible for calm and relief of irritability. That's why Xanax, Valium (diazepam), and Ativan (lorazepam), among others, work. They are all benzos. Valerian root works much the same way that benzo meds work. They also bind to gaba receptors to force more release and or re-uptake (keeps from wasting neurotransmitters and uses them more efficiently) of gaba within the brain. They, however, are not controlled substances as are the meds. Before taking a urine test, list Valerian Root, even though it is not a prescribed medicine. That is perfectly ok. Even still, Valerian root will usually vanish from the urine stream between 1 and 7 days. St. John's Wort should not provide any false positives, but the key words are should not. It is also a perfectly legal and over the counter herbal supplementation, and is believed to work as a serotonin - nor-epinephrine - dopamine re-uptake inhibitor. It's efficacy is debatable, but the point is that it does not bind to receptors the way that gaba neurotransmitters need in order to work. SJW simply causes the three neurotransmitters to stay within the synapse (a kind of space) between nerve endings instead of being wasted whenever they do not transmit through the receiving nerve ending membrane initially. SJW will keep the neurotransmitters in place until the nerve's membrane becomes excited again by electrical impulses. The electricity allows the membrane to become permeable and receive the neurotransmitters. Because some herbs work in the same mannerism as FDA approved medications, it is possible to show up as those drugs. This is a crude explanation, and illustrations of how neurotransmitters send and receive in the synapses between nerves would be helpful.
Xanax will show up as benzodiazepines, so will valium. The other two substances are perfectly legal and will not test positive. Valerian root does not contain benzodiazepines, despite having some sedative effects.