nepodnošljiv

1. (of pain, heat, a situation) unbearable; intolerable
   Vrućina u gradu je danas nepodnošljiva. — The heat in the city is unbearable today.
   Imao sam nepodnošljiv bol u leđima. — I had unbearable back pain.
2. (of a person) insufferable; impossible
   Kad je umoran, postaje potpuno nepodnošljiv. — When he's tired, he becomes completely insufferable.

The person who can't bear something goes in the dative: meni je to nepodnošljivo.