Oxytocin
Nasally administered oxytocin has been reported to reduce fear, possibly by inhibiting the amygdala (which is thought to be responsible for fear responses). Indeed, studies in rodents have shown oxytocin can efficiently inhibit fear responses by activating an inhibitory circuit within the amygdala. Some researchers have argued oxytocin has a general enhancing effect on all social emotions, since intranasal administration of oxytocin also increases envy and "Schadenfreude". Individuals who receive an intranasal dose of oxytocin identify facial expressions of disgust more quickly than individuals who do not receive oxytocin. Facial expressions of disgust are evolutionarily linked to the idea of contagion. Thus, oxytocin increases the salience of cues that imply contamination, which leads to a faster response because these cues are especially relevant for survival. In another study, after administration of oxytocin, individuals displayed an enhanced ability to recognize expressions of fear compared to the individuals who received the placebo. Oxytocin modulates fear responses by enhancing the maintenance of social memories. Rats that are genetically modified to have a surplus of oxytocin receptors display a greater fear response to a previously conditioned stressor. Oxytocin enhances the aversive social memory, leading the rat to display a greater fear response when the aversive stimulus is encountered again.
Anxiolytic
Opioids are drugs that are usually only prescribed for their painkilling properties, but some research is beginning to find that some varieties are effective at treating depression, obsessive compulsive disorder, and other ailments often associated with or caused by anxiety. They have a very high potential for abuse and have one of the highest addiction rates for all drugs. Many people become addicted to these drugs because they are so effective at blocking emotional pain, including anxiety. Similarly to alcohol, people with anxiety disorders are more likely to become addicted to opioids due to their anxiolytic effect. These drugs range from the commonly prescribed hydrocodone, to the often illegal heroin, and all the way to much more potent varieties like fentanyl often used in trauma or end of life pain management. Most people purchasing these drugs illegally are seeking them out to get a euphoric like high, but many others seek them out because they are so effective at reducing both physical pain and emotional pain.