How To Get Rid Of Fleas With Lemon Juice. There are a couple of different ways to use lemon juice to kill fleas or as a repellent. Mix 1/4 cup of lemon juice into 2 to 3 cups of baby shampoo.
Mix equal parts lemon juice and water and use it to mop floors to kill and repel fleas. The lemon juice repels and kills fleas and the shampoo smothers them. Just as with apple cider vinegar, fleas are repelled by the sharp, pungent scent and flavor of citrus juices, especially lemon juice.