There has been a lot of research done over the years testing the benefits of drinking aloe vera juice and aloe vera gel. The results have clearly shown there are some medicinal benefits of Aloe vera juice and gel. However, it is important to understand that there are potential Aloe vera juice side effects and also Aloe vera gel side effects. Some professionals consider consuming Aloe vera to be safe and point out the fact that side effects are rare. Nevertheless, not everyone has that same confidence that drinking Aloe vera is without concerns.
Before discussing the actual side effects it should be noted that not all Aloe vera juice is the same! Even if you make the Aloe juice yourself you should be aware that each batch can vary depending on the plants themselves. The nutritional benefits, as well as the unwanted components, will vary depending on the age of the plant and where it was grown among other things. That is also true of commercially processed Aloe vera juice. Additionally, with retail purchased Aloe vera juice and gel there is a wide variety of processing techniques and the types of additives that may be included in the ingredients. Most retail products use the Aloe vera barbadensis miller variety since this has been shown to have the best health benefits among hundreds of varieties.
Possible Aloe Vera Juice Side Effects
People experience the most undesirable side effects when the Aloe vera juice is processed from the whole leaf and it still contains the latex. Even a small amount of latex in the Aloe juice may cause abdominal cramps, diarrhea, nausea, vomiting, dehydration and low potassium levels. It is not common but some people are allergic to Aloe. If you are allergic to garlic or onions be particularly cautious because you may also be allergic to Aloe vera juice and gel.
Other Potential Risks and Contraindications
Pregnant or breastfeeding women are advised not to consume Aloe vera juice or gel. Some feel there is a connection between breastfeeding women consuming Aloe vera and infants having gastrointestinal issues.
Using Aloe orally, according to some reports published by the American Cancer Society, point to the possibility that any long-term use may lead to Aloe vera side effects including hepatitis or even increase the risk of cancer.
According to the Memorial Sloan-Kettering Cancer Center, Aloe juice and gel has the potential to interact with some prescription medications and may also increase the risk of bleeding during surgery. It has been suggested that continued use may lead to thyroid problems.
Those frequently experiencing low blood pressure should be cautious since drinking Aloe may further cause blood pressure to drop.
The Mayo Clinic advises people with electrolyte abnormalities or heart disease to only use Aloe cautiously. They advise avoiding Aloe altogether “in people with abdominal pain that is sudden and severe, appendicitis, bowel obstruction, fecal impaction, kidney disease, liver disease, or in people taking agents toxic to the liver. Avoid use as an injection, during postoperative incision healing…”
Although it does not comment on the topical use of Aloe vera, the Center for Science in the Public Interest recommends simply avoiding the oral use in any form.
History of Side Effects of Aloe Vera Juice and Gel
For many years, Aloe vera was the primary ingredient in most over-the-counter laxatives. The whole leaf was used in the products and it was very effective. However, in 2002 the FDA pulled from the market all laxatives containing Aloe vera. Their justification for this move was that there was simply not enough evidence to prove the safety of consuming Aloe vera.
A two-year study conducted by the National Toxicology Program raised further concerns concerning drinking Aloe vera juice. After giving rats an extract of the Aloe vera whole-leaf researchers reported “clear evidence of carcinogenic activity in male and female rats, based on tumors of the large intestine.”
It should be noted that the study was conducted with extract of whole-leaf Aloe vera that was non-decolorized. Today most manufacturers (not all) decolorize the Aloe leaf by passing it through charcoal filters. This is done specifically to remove the anthraquinones which are responsible for the laxative properties. This process removes Aloin, the anthraquinone which some researchers suspect is the primary cause of the rats developing tumors.
An interesting study by researchers in the U.K. in 2004 obtained very different results.  Their study was done with patients that already had ulcerative colitis which is an inflammatory bowel disease. For four weeks each patient drank Aloe vera gel (not the juice) and water twice per day. The results proved an improvement and even some remission of the ulcerative colitis compared to the control group which just got water. Additionally, there were no tumors that developed or any other significant side effects of Aloe vera among those that drank the Aloe vera gel.
So there are a number of studies that show both positive and negative aspects to drinking Aloe vera juice or using the gel. As an example, contrasting the tumor producing study mentioned earlier, another report stated, “Aloe-emodin (an anthraquinone) given to mice in which tumor cells had been injected inhibited growth of malignant tumors. Other animal data also suggest that components of Aloe inhibit tumor growth and improve survival.” 
The topical use of Aloe vera for medicinal reasons seems to have universal acceptance. Many use Aloe vera for wrinkles and other skin conditions. However, the oral use of Aloe vera, both the juice and the gel, has some people very cautious. Like any other product, it should also be noted that every individual may experience their own unique positive and/or negative reactions. Be sure to do your research and consult with your medical professional before you drink Aloe vera juice or use the gel.
If you do choose to consume Aloe vera after consulting your doctor, be sure it does not contain any Aloin. The better Aloe vera manufacturers will always make this clear on the packaging. Whenever possible choose a brand of organic Aloe vera juice. If you experience any new negative symptoms immediately stop consuming the Aloe and contact your doctor.