Aloe vera may be topically applied to flea bites in order to relieve the itching and inflammation, as long as the skin is not broken or bleeding.
Aloe helps to soothe the skin and is more well-known as a treatment for sunburned skin, but it can also be used for flea bites with good effect.
In addition to aloe vera, you may wish to topically apply calamine lotion if you happen have that in your medicine cabinet because it will help with flea bite symptoms.
Hydrocortisone cream from your local pharmacy will also help to relieve the irritation and skin rash.