18:38
विषयेन्द्रियसंयोगाद्यत्तदग्रेऽमृतोपमम् ।
परिणामे विषमिव तत्सुखं राजसं स्मृतम् ॥१८- ३८॥
wiShayendriyasaMyogaadyattadagre'mRRitopamam ।
pariNaame wiShamiwa tatsukhaM raajasaM smRRitam ॥१८- ३८॥
Source: Automatic ITRANS Transliteration
That from contact of perceptions with objects, which though at first is comparable to nectar of immortality, but
Is in effect like poison, that joy remember as rajasic.
Source: Milind S. Pandit
Sensual pleasures appear as nectars in the beginning, but become poison in the end; such pleasures are called Raajasika pleasures. (See also 5.22)
That happiness which is derived from contact of the senses with their objects and which appears like nectar at first but poison at the end is said to be of the nature of passion.
Source: Bhagavad Gita As It Is