Natural Factors Stress-Relax Kava Kava 250mg Stress-Relax Kava Kava is standardized to contain 30% kavalactones, the key active constituents in kava.* Kavalactones support the production of the neurotransmitters involved in regulating mood and relaxation, including serotonin, dopamine, and noradrenaline. Kava may help calm nervousness, relax tense muscles, and minimize the negative effects of stress, as well as having possible analgesic (pain-relieving) qualities.