Aloe vera has no contra-indications since it consists of a non-toxic substance with unlikely reactions to any conventional medications. I encourage you to do a patch test if you are susceptible to allergic reactions. Some sources warn to not take internally if you are pregnant. This has been disproved by many successful cases. Many anthraquinones in the Aloe vera cause intestinal cramping.68 Some doctors warn about using Aloe vera internally. They need to address the use of the rind vs. the pulp. The rind consists of aloin and emodin, anthraquinones, which are cathartics that can be strong purgatives. The pulp of Aloe vera has no aloin or emodin properties making it completely non-toxic.69 People taking prescription medications need to be alerted that Aloe vera may enhance the action of the drugs or herbal preparations such as with insulin for a diabetic.70