Being in love is physically similar to the buzz of taking drugs and also has withdrawal symptoms, an expert on addiction has said.
The brain can give itself a natural high
Dr John Marsden says dopamine - the drug released by the brain when it is aroused - has similar effects on the body and mind as cocaine or speed.
"Attraction and lust really is like a drug. It leaves you wanting more," the National Addiction Centre head said.
His findings will appear in a BBC programme to be broadcast next month.
"Being attracted to someone sparks the same incredible feelings no matter who you are. Love really does know no boundaries," he said.
According to Dr Marsden - a chartered psychologist - the brain which processes emotions becomes "fired up" when talking to someone it finds attractive.
The heart pounds three times faster than normal and causes blood to be diverted to the cheeks and sexual organs, which causes the feeling of butterflies in the stomach, he says.
However, as with cocaine and speed, the "hit" is only temporary, though it can last between three and seven years, he added.
Dr Marsden's research for the BBC's Body Hits series suggests people look for similar features to themselves in a partner as they are searching for characteristics in their mother and father, who have already successfully raised a child.
"It might look like we are all after the perfect partner to wine and dine but underneath, our animal instincts are seeking
out an ideal mate to share our genes with."
"We tend to go for the smell of somebody who has a very different immune system and that stops you fancying your family.
"Our biology drives us to find a perfect compromise between sameness and difference and we strike that balance all the time when it comes to choosing faces and smells," he said.
The research also suggests sex is booby-trapped to make partners bond.
"Your body has evolved over millions of years with one aim - to go forth and multiply, so while having kids may not be on the agenda just yet your body has a few tricks up its sleeve to drag you in that direction," he said.
According to the research the more two people have sex together, the more likely they are to bond.
"We all know you can have sex without falling in love but if you have enough sex with the same person there's a good chance you will hit the body's booby-trap which is there to tip you head over heels into love," said Dr Marsden.
"So your body goes all out to make you bond with your partner and that makes love highly addictive and the withdrawal sucks."
Body Hits: Love Story is on BBC Three on Thursday 4 December at 2100 GMT.