Aloe Vera

• Aloe vera is three different products: only the clear inner-leaf gel is the 'gentle' one. The clear gel from the middle of the leaf is used on skin and sold as juice. The bitter yellow latex just under the leaf skin contains aloin and other anthraquinones that act as a strong stimulant laxative. Whole-leaf extracts can contain both. A 'decolorized' whole-leaf extract has the anthraquinones filtered out; a 'non-decolorized' one does not. Most safety problems below belong to the latex and the non-decolorized whole-leaf extract, not to the gel. Product labels do not always say which one you are buying, so check the label or ask the maker. Authoritative guidance ^{36 64 65 20}
• Aloe latex and aloin are strong laxatives that can cause cramps, diarrhoea and potassium loss. The EU monograph on aloe dried leaf juice limits it to occasional constipation, for no more than one week, and contraindicates it in pregnancy, breastfeeding, children under 12, bowel blockage, inflammatory bowel disease, abdominal pain of unknown cause and severe dehydration. Long use can cause dependence, loss of water and salts, and urine changes. The US FDA required aloe latex to be taken out of over-the-counter laxatives in 2002 because of a lack of safety data (as reported by NCCIH). Authoritative guidance ^{59 64 60}
• Non-decolorized whole-leaf extract caused bowel cancers in rats and is rated 'possibly carcinogenic to humans'. In a two-year US National Toxicology Program study, rats given non-decolorized whole-leaf extract in their drinking water developed large-intestine cancers that were not seen in controls, and both rats and mice developed bowel overgrowth (hyperplasia). The International Agency for Research on Cancer classified this extract as possibly carcinogenic to humans (Group 2B) based on animal evidence, and California lists it under Proposition 65. This is animal evidence on one type of extract. Human studies of related anthranoid laxatives did not find a higher colorectal cancer risk, but they were not about aloe and are older. Decolorized extracts have the anthraquinones removed and are not the material that was classified. Animal research ^{8 62 65 20 38 35 29}
• Oral aloe products have been linked to liver injury. LiverTox says oral forms of aloe vera have been linked to rare instances of clinically apparent liver injury. Published case reports describe acute hepatitis in people who took oral aloe capsules or preparations for weeks to months, with liver tests returning to normal after stopping. NCCIH says leaf extracts used for as little as 3 weeks and as long as 5 years have been linked to acute hepatitis. The products in the reports were not always described, so we cannot tell if gel, latex or whole-leaf extract was responsible. Stop and get care for yellow skin or eyes, dark urine or pale stools. Case report ^{37 6 56 64 59}
• Do not use aloe latex or oral laxative aloe in pregnancy or while breastfeeding. The EU monograph contraindicates aloe dried juice in pregnancy because several anthranoids (including emodin and aloe-emodin) showed genotoxic risk in experiments, and in breastfeeding because related anthranoid metabolites pass into breast milk in small amounts. NCCIH says oral aloe in gel, latex or whole-leaf form may be unsafe in pregnancy and breastfeeding. LactMed says aloe latex should not be used while breastfeeding; aloe gel on the nipples should be washed off before feeding because the taste may upset the baby or cause diarrhoea. Authoritative guidance ^{59 64 36}
• Kidney disease, heart rhythm medicines and diuretics need extra care with aloe latex. The EU monograph says long use can cause water and salt imbalance, and albuminuria and haematuria; people with kidney disorders should be aware of electrolyte imbalance. Low potassium from laxative use can strengthen the effect of heart medicines such as digoxin and affects heart rhythm drugs; diuretics, steroids and liquorice can add to potassium loss. NCCIH also warns about aloe latex and digoxin-type drugs. Ask a doctor or pharmacist before using aloe latex with any of these. Authoritative guidance ^{59 64 20}
• Tell the surgical team if you take oral aloe before an operation. One case report links oral aloe vera tablets and the anaesthetic sevoflurane to heavy bleeding during surgery. That is a single report of a possible interaction, so it does not show cause. It is a reason to mention aloe to your surgeon and anaesthetist. Case report ³²
• Aloe gel on the skin can cause irritation or allergy in some people. Aloe gel is usually well tolerated. NCCIH reports occasional burning, itching, rash and eczema. A trial in breast radiotherapy found rare contact dermatitis from the gel, one case report documents allergic contact dermatitis to home-made leaf juice, and a patch-test study of 702 patients found no sensitization. Irritation may sometimes come from latex contamination of the gel. Stop use if you get a rash. Case report ^{64 54 18 45 36}

LiverTox says oral forms of aloe vera have been linked to rare instances of clinically apparent liver injury. We read two published reports: a 73-year-old woman admitted with acute hepatitis after using oral aloe vera capsules for constipation, whose liver markers returned to normal after she stopped (causality rated possible on the Naranjo scale and probable on RUCAM; the authors used the more cautious label), and three Korean women (55 to 62 years) who took aloe preparations for months and had toxic hepatitis by RUCAM, with liver enzymes returning to normal after stopping. NCCIH says oral leaf extracts used for as little as 3 weeks and as long as 5 years have been linked to acute hepatitis. The EU monograph also warns that chronic overdose of anthranoid-containing medicines may lead to toxic hepatitis. None of the sources read says which part of the plant or which product caused the injury. ^{37 6 56 64 59}

How often. No frequency was found. LiverTox calls the injury rare. The case reports show that injury can happen, not how often. The LiverTox likelihood score was not read.

Monitoring. No agency monitoring advice was read. Stop and seek care for yellow skin or eyes, dark urine, pale stools, right-upper belly pain, or marked tiredness; tell your doctor about all herbal products.

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This is a safety connection. It is not evidence that Aloe Vera supports liver health.

Summary. Aloe vera gel on skin is generally well tolerated, and oral gel up to about 42 days appeared safe in research studies (NCCIH). The main toxicity concerns are the latex anthraquinones (aloin and relatives), which are laxative and irritating, and the non-decolorized whole-leaf extract, which caused bowel cancers in rats. Reviews also link ingestion of aloe preparations to diarrhoea, low potassium, pseudomelanosis coli, kidney problems and liver injury.

Animal. US National Toxicology Program (Boudreau 2013, TR-577): groups of 48 rats received a non-decolorized whole-leaf extract of Aloe barbadensis Miller in drinking water at 0.5, 1 or 1.5% for 2 years, and mice at 1, 2 or 3%. Large-intestine hyperplasia rose markedly in all treated groups; rats also had small-intestine, stomach and lymph node hyperplasia; and large-intestine cancers appeared in male and female rats given the extract but none in control rats of this and other studies at the laboratory. Mice had large-intestine and lymph node or stomach hyperplasia. The EU monograph adds that emodin, a constituent of aloe dried juice, affected oestrous cycle length in rats and caused kidney damage in mice, and that long-term studies reported effects on kidney and colon or caecum.

Human doses studied. Oral aloe vera gel at 100 mL twice daily for 4 weeks in a small ulcerative colitis trial had minor adverse events similar to placebo; an aloe syrup at 10 mL a day for 4 weeks in a reflux trial had no adverse events requiring withdrawal. NCCIH says short-term oral gel use up to 42 days appears safe in research studies. The EU monograph's laxative dose is expressed as 10 to 30 mg hydroxyanthracene derivatives (as aloin), once at night, for at most a week.

High dose or long term signals. Long use of aloe latex: dependence, water and electrolyte loss, albuminuria, haematuria, pseudomelanosis coli (EMA). Oral aloe extracts and capsules: acute hepatitis case reports over weeks to years (NCCIH, case reports). Reviews list kidney failure as an association with ingestion, but the underlying case reports were not read.

Overdose response. The EU monograph says the main symptoms of overdose or abuse are griping pain and severe diarrhoea with loss of fluid and electrolytes, treated with generous fluids and monitoring of potassium, especially in older people. Chronic overdose of anthranoid medicines may lead to toxic hepatitis.

Genotoxicity. The EU monograph says no preclinical tests were available for aqueous aloe extracts, and that several hydroxyanthracene derivatives were mutagenic and genotoxic in several in vitro test systems, not proven in vivo. NCCIH says lab research suggests even decolorized extract might damage DNA or chromosomes. A 2023 review of the literature (Kim) concluded drinkable inner-leaf gel and decolorized whole-leaf products with no more than 10 ppm aloin are not genotoxic; NCCIH cites it, and we did not check the authors' ties to the industry. Human data on anthranoid laxatives and colorectal cancer: a prospective case-control study (Nusko 2000; 202 cancers, 114 adenomas, 238 controls) found no raised risk (odds ratio 1.0), an Italian study (Nascimbeni 2002) did not support a link using early bowel lesions as a marker, and the Melbourne study (Kune 1993; 685 cases, 723 controls) found no association. These studies covered anthranoid laxatives in general, not aloe alone.

Toxic plant parts. The plant part used is the leaf. The clear inner gel is the main material for skin and drinks. The latex (bitter yellow juice from just under the skin) contains aloin and other anthraquinones and is the laxative material (LactMed, EMA). Whole-leaf extracts contain both unless filtered. Toxicity of roots, flowers or other aloe species was not reviewed here; aloe species other than A. vera (for example A. ferox) are used in the EU monograph and should not be assumed to behave the same.

The key quality issue is how much aloin (latex anthraquinone) a product contains, which depends on how the leaves were processed. We found no survey of heavy metals, pesticides or adulteration in aloe supplements.

Aloin content depends on processing. In Greek aloe vera leaf gel products (Kaparakou 2021), samples processed industrially or filtered in the lab had aloin below the limit of 0.1 mg per litre that the paper cites for EU legislation, but unprocessed and unfiltered samples contained more than 10 mg per litre. ²⁷

Decolorized vs non-decolorized whole-leaf extract. OEHHA states that most consumer products contain decolorized whole-leaf extract (filtered to remove cancer-causing chemicals), that a few contain the non-decolorized extract, and that labels do not always make this clear. NCCIH notes that the decolorized form has toxic anthraquinones removed. ^{65 64}

Home-made leaf juice. OEHHA advises that if you make remedies from whole leaves, the plant's harmful chemicals should be removed, for example by filtering through an activated charcoal filter; a case report describes allergic contact dermatitis from home-made aloe leaf juice on the legs. ^{65 18}

Supplements in general. LactMed warns that supplements can differ from their labels and that results on one product may not apply to another. ³⁶

• Swelling of the face, lips or throat, trouble breathing or widespread hives after aloe: call emergency services.
• Yellow skin or eyes, dark urine, pale stools, severe tiredness or pain in the upper right belly after taking oral aloe: stop and see a doctor the same day.
• Severe or bloody diarrhoea, severe belly pain, vomiting, marked weakness, muscle cramps or a fluttering or irregular heartbeat after a laxative aloe product (possible low potassium or dehydration): get urgent care.
• Blood in the urine or foamy urine, or very little urine, after long use of aloe laxatives: see a doctor.
• A rash, blistering or swelling where aloe was applied: wash it off, stop using it, and see a clinician if it does not settle.
• Skin that is red, hot, painful or oozing around a wound treated with aloe, or a burn that is large, deep, blistering over a large area or on the face, hands or genitals: seek medical care rather than self-treatment.
• Any laxative-type aloe in pregnancy or while breastfeeding, or given to a child under 12: stop and ask a doctor or pharmacist.
• Heavy bleeding during or after surgery in someone who took oral aloe: tell the team about the aloe.

Stop the supplement and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.