halahala | हालाहल

halahala (Devanagari: हालाहल​ ISO15919: hālāhala) is the virulent poison produced during the churning of the milk ocean Kshirasagara.

All devatas and rakshasa became unconscious due to the fumes of that poison. Lord Shankara saved them all by swallowing it and holding it in His throat turning his throat blue. Thus, earning Him the title of Nilakantha, the blue-throated one.

Also written as haalaahala, halahal

Reference: Prema Rasa Madira - The Intoxicating Bliss of Divine Love, Vol. 1, Ch. 7