Use and effects
Properly-synthesized aurora is a dark purple liquid, tasting vaguely like bitter spearmint, that is traditionally ingested orally in doses of 2cc. Users with a heavier tolerance, or who prefer a more intense high, often pour the same amount directly into their eyes and absorb it through the tear ducts and cornea (referred to as 'praying' for euphemistic reasons, which resulted in aurora being nicknamed 'Athame' in asari circles). It is also commonly taken in tea.
When ingested, aurora stimulates serotonin vesicles in order to induce relaxation in the user. Hallucinogenic effects also cause the user to see coronas of colorful light around objects, hence the drug's name. Ingestion of more than double the recommended dose tends to cause a euphoric fugue state.
Addiction and long-term effects
Aurora can be used responsibly but rarely is. Although it takes a considerable amount of use to make the user physically addicted, the euphoria of aurora use is potent enough that a psychological addiction will generally result in chemical dependency.
Long-term overuse of aurora damages the neural synapses, with several detrimental effects. The user's long-term memory is usually burned out due to lack of synapse reinforcement, and the somatosensory system becomes hypersensitive, causing extreme reactions to skin contact.
Legality and cultural significance
Due to different cultural perspectives on recreational drug use, the legality of aurora varies depending on territorial authority. The Asari Republics and the Turian Hierarchy allow it to be traded and consumed without regulation, placing the burden of responsible use on the individual, while the Salarian Union requires businesses who wish to distribute aurora to qualify for a license, which is retained on the condition that they promote responsibility in their clientele's usage habits. The Systems Alliance and Batarian Hegemony prohibit possession, distribution, or usage of aurora. However, humans on the Citadel are free to do so, owing to the station being under Council rather than Alliance jurisdiction.
Aurora's popularity with the artistic community led to a glut of artwork featuring the familiar drug-induced corona during the abstract expressionist period of 2080, as well as the rise of 'shinesleeves', shoulder-length gloves that partially mitigate the hypersensitivity caused by overuse. Shinesleeves occasionally go in and out of vogue with non-aurora users, since the people who most commonly need them tend to be wealthy and fashionable, but their appearance in holo dramas or other fictional entertainment is almost always shorthand meaning the character wearing them is an addict (or, at the very least, rich).
Cerastes is a user of aurora; he's noted that these days it's as extreme as he gets, drug-wise.