A single flea can lay up to 60 eggs in one day, easily leading to a flea infestation on your cat, according to Eartheasy. While you can purchase a commercially available flea shampoo to wash away the fleas, you can avoid the toxic chemicals in these products by using ones with natural ingredients instead. Make your own flea repellent shampoo for your cat that will eliminate fleas, discourage new fleas, and soothe your cat's irritated skin using natural, nontoxic ingredients.
Boil 296 ml (1 1/4 cups) of water on the hob in the saucepan and add three rosemary sprigs. Remove the pan from the heat and allow the rosemary to steep in the water. Wait until the water becomes warm to the touch, then remove the rosemary sprigs. The essence of rosemary will help kill existing fleas and prevent new ones.
Mix in 110 g (1 cup) Castile soap, 237 ml (1 cup) apple cider vinegar, 1 tsp glycerine and 1/2 tsp neem oil to the warm rosemary water. Neem has excellent pest control properties to repel fleas, as does the vinegar. Continue to stir the mixture until you combine all of the ingredients. Put it aside.
Grind 37.5 g (1/4 cup) dry oats in a food processor or blender until you obtain the consistency of fine powder. Add the ground oats to the mixture and stir it in well. The oat powder will sooth your cat's itchy skin from flea bites.
Pour the mixture into an empty, resealable 1 1/2 litre (1 1/2 qt) bottle or jar. Before using it to wash your cat, shake it well.
Bathe your cat using this shampoo weekly to eliminate fleas from its coat and soothe any irritations on its skin.
Shampoo your cat weekly to ensure no new fleas infest your home. Keep your cat indoors to prevent it from picking up fleas. Brush your cat with a flea comb before and after bathing to fully remove all of the fleas. Wash all of your cat's bedding and vacuum carpeting to eliminate fleas in your home.
Never use essential oils on your cat as they can build up toxic levels in its system over time.