While avocados are an incredibly healthy fruit, there are some drawbacks to eating them every day. Some people are allergic to avocados. Eating one may cause them to have a rash, severe swelling, itching, or eczema. It increases serum IgE levels in your body and can cause problems for those who have latex allergies.  Besides allergies, avocados have a few other health side effects. It acts as a natural blood thinner. If you are on blood-thinning medication, you may want to be careful with your avocado intake. While avocado contains healthy fat, if you consume enough avocado, you may begin to gain weight.