Where can i buy tea tree oil shampoo in stores?

i need tea tree oil shampoo but i'm not sure where i can buy it. there is a certain brand that i heard was good its called Desert Essence Tea Tree Shampoo with Organic Tea Tree Oil. My niece has contractrd lice from one of her friends and i'm trying to find something to prevent others in her household from getting it and i've read that tea tree oil does the job. any other suggestions??Where can i buy tea tree oil shampoo in stores?
Sally's sell generic version of Paul mitchell green tea shampoo and Givanni ';Riteaid';

stila