As with other slow lorises, this arboreal and nocturnal species primarily eats insects, tree gum, nectar, and fruit and has a toxic bite, a unique feature among primates.

[6] In 1971, that view was updated by distinguishing the pygmy slow loris (N. pygmaeus) as a species, and by further recognizing four subspecies, including N. coucang menagensis.

[10] A 2013 review of museum specimens and photographs attributed to N. menagensis resulted in elevating two of its former subspecies to species: N. bancanus and N. borneanus.

[13] It also possesses a specialized arrangement of lower front teeth, called a toothcomb, which is also used for grooming, as with other lemuriform primates.

[15] On the ventral side of its elbow, it has a small swelling called the brachial gland, which secretes a pungent, clear oily toxin that the animal uses defensively by wiping it on its toothcomb.

[17] Like other slow lorises, N. borneanus is arboreal, nocturnal,[12] and omnivorous, eating primarily insects, tree gum, nectar, and fruit.

Their toxic bite is a deterrent to predators, and the toxin is also applied to the fur during grooming as a form of protection for their infants.

When threatened, slow lorises may also lick their brachial glands and bite their aggressors, delivering the toxin into the wounds.

[21] Between 1987 and 2012, one-third of Borneo's forests have been lost, making habitat loss one of the greatest threats to the survival of N. borneanus.