Drew Barrymore always takes her boyfriend's sweaty t-shirts away with her.

The 'Going the Distance' actress - who refuses to confirm if she is still in a relationship with actor Justin Long - thinks falling in love is strongly connected to a person's smell and says her lover's scent is always the thing she misses most.

She explained: "Love smells good - like somebody's skin.

"It's amazing to me that, when you fall in love with someone, you just start to love the way they smell. If I have to go away from someone I say, 'Wear this t-shirt for five days in a row, then I'm going to take it with me."

The 35-year-old star also claimed having sex with someone can ruin a friendship.

She said: "The minute you have sex, it changes everything.

"Don't tell me it hasn't happened to you. You f***ed a friend and you're like, 'S**t, it's not going to be the same. We had everything. Why did you f**k me?' And then you can't be friends any more."

Despite her claims, Drew - who was previously married to bar owner Jeremy Thomas and comic Tom Green - claims to have stayed friends with all her ex-boyfriends.

She added in an interview with Marie Claire magazine: "I'm trying to think of who I've slept with who I'm still good friends with. er, Justin? Actually, I'm good friends with all of my exes."