Take out 2 pills and set them aside.
Then weigh 3 out of the remaining 6 pills against the other 3.
If they balance then the poisonous pill is one of the 2 you took out and one 1 against 1 weighing will identify it.
If the 3 do not balance then you know that the poisoned pill is one of the heavier trio.
Remove one pill from these 3 and weigh the other 2. If one is heavier then you have the posined pill. If they weigh the same then the one taken out is the poisoned one.
