Aloe

Aloe vera and its relatives have a long record of use across many cultures for burns and wounds, as an antiseptic and anti-inflammatory, and as a laxative ^{29Reference 29Reynolds et al. · 1999ReviewAloe vera leaf gel — a review updateView study →}.

The laxative use is recognised in Europe today. The EU herbal monograph classes the dried leaf juice of Aloe barbadensis and Aloe ferox as a medicine of well-established use for short-term, occasional constipation, dosed by its hydroxyanthracene content and limited to one week ^{53Reference 53European Medicines Agency · 2016ReviewEuropean Union herbal monograph on Aloe barbadensis Mill. and on Aloe (various species, mainly Aloe ferox Mill. and its hybrids), folii succus siccatus (EMA/HMPC/625788/2015) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-aloe-barbadensis-mill-and-aloe-various-species-mainly-aloe-ferox-mill-and-its-hybrids-folii-succus-siccatus_en.pdfView study →}.

Aloe is Lu Hui, and Chinese practice uses the dried, concentrated latex rather than the gel. It is bitter and cold, and enters the Liver and Large Intestine channels ^{37Reference 37Wu · 2005An Illustrated Chinese Materia Medica}.

It is given to clear liver heat and to move a stalled bowel. The classical indication is constipation from heat accumulation, particularly where the heat also disturbs sleep with a restless insomnia ^{37Reference 37Wu · 2005An Illustrated Chinese Materia Medica}.

It is not given in pregnancy, or to anyone with a cold, deficient spleen or stomach pattern ^{37Reference 37Wu · 2005An Illustrated Chinese Materia Medica}.

In Ayurvedic and Thai medicine, aloe is used for peptic ulcers, burns, wounds, abscesses, mouth ulcers and inflammation ^{36Reference 36Bone · 2003A Clinical Guide to Blending Liquid Herbs: Herbal Formulations for the Individual Patient}.

Topical gel for burns and wounds has the most trial support, and it is the form in everyday use.

A 2024 meta-analysis of nine RCTs, six of which reported healing time, found topical aloe cut mean healing time of second-degree burns by about 3.8 days compared with other topical treatments (MD −3.76 days, 95% CI −5.69 to −1.84), with no increase in infection and no clear pain relief ^{7Reference 7Huang et al. · 2024Meta-analysisEffects of Aloe vera on burn injuries — systematic review and meta-analysis of randomized controlled trialsView study →}.

An earlier meta-analysis of four trials in second-degree burns reached the same conclusion, at about 4.4 days faster to healing ^{8Reference 8Sharma et al. · 2022Meta-analysisSecond-degree burns and Aloe vera — meta-analysis and systematic reviewView study →}.

In a double-blind RCT of split-thickness skin-graft donor sites (12 patients, 24 sites), aloe-treated wounds re-epithelialised faster (11.5 vs 13.7 days, p < 0.05), again without significant pain relief ^{9Reference 9Burusapat et al. · 2018Systematic reviewTopical Aloe vera gel for accelerated wound healing of split-thickness skin-graft donor sites — double-blind randomized controlled trial and systematic reviewView study →}.

Sunburn has been tested in the UV erythema test, where a measured patch of skin is reddened with UVB light. In 40 volunteers, a 97.5% aloe gel reduced the redness after 48 hours, more than 1% hydrocortisone in the same gel base but less than 1% hydrocortisone cream ^{44Reference 44Reuter et al. · 2008RCTInvestigation of the anti-inflammatory potential of Aloe vera gel (97.5%) in the ultraviolet erythema test — randomised controlled trialView study →}. A second study of 40 volunteers compared seven plant extracts, and aloe was the only one whose effect on the redness was statistically significant ^{45Reference 45Beikert et al. · 2013RCTAntiinflammatory potential of seven plant extracts in the ultraviolet erythema test — randomised placebo-controlled studyView study →}. In 20 volunteers, a 70% aloe cream applied before or after UVB exposure gave no protection against sunburn and did not treat it compared with placebo ^{46Reference 46Puvabanditsin et al. · 2005RCTEfficacy of aloe vera cream in prevention and treatment of sunburn and suntan — randomised double-blind trialView study →}.

The gel’s activity is attributed to its acemannan polysaccharide and anti-inflammatory constituents ^{29,31Reference 29Reynolds et al. · 1999ReviewAloe vera leaf gel — a review updateView study →Reference 31Liu et al. · 2019ReviewExtraction, purification, structural characteristics, biological activities and pharmacological applications of acemannan, a polysaccharide from Aloe vera — a reviewView study →}. In mice and in diabetic rats, aloe applied to the skin or given by mouth sped wound healing ^{30,35Reference 30Davis et al. · 1989Wound healing — oral and topical activity of Aloe vera (animal study)View study →Reference 35Chithra et al. · 1998AnimalInfluence of Aloe vera on the healing of dermal wounds in diabetic rats — animal model}. The trials are small and use varied gel preparations, so the size of the benefit is uncertain even though its direction is consistent.

Gap: trials are small, unblinded for a visible gel, and rarely standardise the product — the ~4-day advantage is a pooled estimate across heterogeneous studies, not a fixed effect.

Several meta-analyses converge on a modest glucose-lowering effect in prediabetes and early, untreated type 2 diabetes. Pooling five RCTs, oral aloe reduced fasting blood glucose by about 30 mg/dL and HbA1c by 0.41% versus control ^{1Reference 1Zhang et al. · 2016Meta-analysisEfficacy of Aloe Vera supplementation on prediabetes and early non-treated diabetic patients — systematic review and meta-analysis of randomized controlled trialsView study →}.

A second meta-analysis (eight trials, 470 patients) found significant HbA1c improvement in type 2 diabetes and a smaller fasting-glucose effect in prediabetes, while flagging high heterogeneity and calling for standardised preparations ^{2Reference 2Suksomboon et al. · 2016Meta-analysisEffect of Aloe vera on glycaemic control in prediabetes and type 2 diabetes — systematic review and meta-analysisView study →}.

An umbrella review of four systematic reviews graded the evidence “moderate to high quality” in favour, in both prediabetes and T2DM ^{3Reference 3Araya-Quintanilla et al. · 2021Systematic reviewEffectiveness of Aloe vera in patients with type 2 diabetes and pre-diabetes — an overview of systematic reviewsView study →}.

The signal is corroborated by individual RCTs: a 300 mg gel capsule twice daily for two months lowered fasting glucose and HbA1c in hyperlipidaemic diabetics on standard therapy ^{4Reference 4Huseini et al. · 2012RCTAnti-hyperglycemic and anti-hypercholesterolemic effects of Aloe vera leaf gel in hyperlipidemic type 2 diabetic patients — randomized double-blind placebo-controlled clinical trialView study →}, and an aloe gel complex reduced weight, body fat and insulin resistance in obese prediabetics ^{5Reference 5Choi et al. · 2013RCTMetabolic effects of Aloe vera gel complex in obese prediabetes and early non-treated diabetic patients — randomized controlled trialView study →}.

The authors all note that the underlying trials are small, of poor methodological quality, and use non-uniform “gel” products ^{1,2Reference 1Zhang et al. · 2016Meta-analysisEfficacy of Aloe Vera supplementation on prediabetes and early non-treated diabetic patients — systematic review and meta-analysis of randomized controlled trialsView study →Reference 2Suksomboon et al. · 2016Meta-analysisEffect of Aloe vera on glycaemic control in prediabetes and type 2 diabetes — systematic review and meta-analysisView study →}.

Gap: no large, well-powered trial with a standardised preparation; effects are small and drawn from low-quality studies, and none of this tests aloe against or alongside modern glucose-lowering drugs at scale.

The lipid data come from the same diabetes and prediabetes trials. In the five-RCT meta-analysis, aloe significantly lowered triglycerides, total cholesterol and LDL cholesterol, and raised HDL, alongside its glucose effect ^{1Reference 1Zhang et al. · 2016Meta-analysisEfficacy of Aloe Vera supplementation on prediabetes and early non-treated diabetic patients — systematic review and meta-analysis of randomized controlled trialsView study →}.

The umbrella review likewise reported a significant triglyceride reduction ^{3Reference 3Araya-Quintanilla et al. · 2021Systematic reviewEffectiveness of Aloe vera in patients with type 2 diabetes and pre-diabetes — an overview of systematic reviewsView study →}, and individual RCTs found LDL and total cholesterol fell — in one prediabetes trial only at the higher 500 mg twice-daily dose, and only after eight weeks ^{6Reference 6Alinejad-Mofrad et al. · 2015RCTImprovement of glucose and lipid profile status with Aloe vera in pre-diabetic subjects — randomized controlled trialView study →}.

Older animal work (fatty-streak formation in hypercholesterolaemic rabbits) is consistent but far weaker evidence ^{33Reference 33Dana et al. · 2012The effect of Aloe vera leaf gel on fatty streak formation in hypercholesterolemic rabbits — animal studyView study →}. The lipid effect has been measured only in small, mostly dysglycaemic populations.

For mucositis caused by cancer radiotherapy or chemotherapy the picture is mixed. A 2025 meta-analysis of seven RCTs (355 patients) found aloe significantly reduced severe, grade 3–4 mucositis versus control (OR 0.32, 95% CI 0.15–0.70); in subgroup analysis the benefit held against placebo but not against active comparators like sodium bicarbonate or benzydamine ^{10Reference 10Cássia-Santos et al. · 2025Meta-analysisEffectiveness of Aloe vera in the treatment of oral mucositis — systematic review and meta-analysis of randomized controlled trialsView study →}.

A triple-blind RCT found an aloe mouthwash as effective as benzydamine, not better ^{12Reference 12Sahebjamee et al. · 2015RCTComparative efficacy of Aloe vera and benzydamine mouthwashes on radiation-induced oral mucositis — triple-blind randomized controlled trialView study →}, and an earlier Stanford phase II trial of oral aloe vera gel in head-and-neck patients found no benefit over placebo on any mucositis endpoint ^{11Reference 11Su et al. · 2004RCTPhase II double-blind randomized study comparing oral Aloe vera versus placebo to prevent radiation-related mucositis in head-and-neck neoplasms — randomized controlled trialView study →}.

Gap: benefit is concentrated in severe-grade cases and disappears against active comparators; the one clean oral-gel RCT was null, so the effect size and best delivery form remain unsettled.

A 2022 meta-analysis of nine trials (847 participants, seven pooled) found aloe produced better overall clinical efficacy than comparators (RR 2.25, 95% CI 1.25–4.06) and, in two studies, shorter healing time — while showing no statistically significant advantage in pain scores or ulcer size, and with very high heterogeneity between studies ^{13Reference 13Zou et al. · 2022Meta-analysisEffects of Aloe vera in the treatment of oral ulcers — systematic review and meta-analysis of randomised controlled trialsView study →}.

The trials consistently report faster healing of the lining and very few side effects. A broader meta-analysis of aloe for mucocutaneous problems found the same pattern: benefit on lesion severity, no significant advantage on pain ^{32Reference 32Gok Metin et al. · 2021Meta-analysisEffects of Aloe vera in adults with mucocutaneous problems — systematic review and meta-analysisView study →}.

Gap: the pain and ulcer-size endpoints were not significantly better than controls, heterogeneity is very high, and “oral ulcers” pools several distinct conditions.

A 2022 cumulative analysis of 14 RCTs (1,572 patients) found aloe pretreatment lowered overall radiation-dermatitis risk (RR 0.76) and, in subgroups, grade 2 and grade 3 reactions specifically ^{16Reference 16Wang et al. · 2022Systematic reviewAloe vera for prevention of radiation-induced dermatitis — systematic review and cumulative analysis of randomized controlled trialsView study →}.

An older self-controlled trial (60 patients, each acting as their own control) likewise found aloe halves reliably less inflamed than untreated halves ^{17Reference 17Haddad et al. · 2013Clinical trialAloe vera for prevention of radiation-induced dermatitis — a self-controlled clinical trialView study →}.

A multicentre double-blind RCT (120 head-and-neck patients) found aloe reduced the severity of established erythema and moist desquamation in later treatment weeks but showed no preventive benefit versus placebo ^{18Reference 18Tungkasamit et al. · 2022RCTReduction in severity of radiation-induced dermatitis in head-and-neck cancer patients treated with topical Aloe vera gel — randomized multicenter double-blind placebo-controlled trialView study →}, and a 2005 systematic review of RCTs found no evidence that topical aloe prevents radiation skin reactions ^{19Reference 19Richardson et al. · 2005ReviewAloe vera for preventing radiation-induced skin reactions — a systematic literature reviewView study →}.

Gap: trials disagree on whether aloe prevents versus merely softens radiation dermatitis, heterogeneity is high (I² ≈ 80%), and no benefit is seen for the worst grade-4 reactions.

Two systematic reviews reach different conclusions from overlapping evidence. A direct meta-analysis of five trials found only weak evidence that aloe beats placebo, a similar effect to topical triamcinolone, and rated aloe “inferior to the control in general” on pooled analysis, while noting it caused no adverse effects, unlike corticosteroids ^{14Reference 14Ali et al. · 2017Meta-analysisThe efficacy of Aloe vera in management of oral lichen planus — systematic review and meta-analysisView study →}.

A later network meta-analysis of 55 trials placed aloe among the interventions significantly better than placebo for pain resolution (OR 13.0, 95% CI 1.5–111.8), though it ranked topical corticosteroids as the most effective class overall ^{15Reference 15Sridharan et al. · 2021Meta-analysisInterventions for oral lichen planus — systematic review and network meta-analysis of randomized clinical trialsView study →}.

Gap: the two meta-analyses disagree on whether aloe beats placebo at all, so its place beside standard corticosteroid treatment is unresolved.

A 1996 double-blind RCT of a 0.5% aloe extract cream reported an 83% “cure” rate versus 6.6% for placebo ^{20Reference 20Syed et al. · 1996RCTManagement of psoriasis with Aloe vera extract in a hydrophilic cream — placebo-controlled double-blind study (randomized controlled trial)View study →}, and a 2010 RCT found aloe cream reduced PASI scores at least as well as 0.1% triamcinolone acetonide ^{22Reference 22Choonhakarn et al. · 2010RCTA prospective, randomized clinical trial comparing topical Aloe vera with 0.1% triamcinolone acetonide in mild to moderate plaque psoriasisView study →}.

A 2005 right/left double-blind trial found a commercial aloe gel performed worse than placebo, with a high placebo response likely reflecting the vehicle ^{21Reference 21Paulsen et al. · 2005RCTA double-blind, placebo-controlled study of a commercial Aloe vera gel in the treatment of slight to moderate psoriasis vulgaris — randomized controlled trialView study →}.

A meta-analysis of plant extracts for psoriasis judged the aloe evidence to provide only limited support (pooled RR 3.37 across placebo-controlled studies) and stressed that small size and methodological weakness prevent firm conclusions ^{23Reference 23Deng et al. · 2013Meta-analysisPlant extracts for the topical management of psoriasis — systematic review and meta-analysisView study →}.

Gap: the 83% result has not been reproduced in later, better-controlled trials; preparation and vehicle differences may explain the disagreement.

In a 2004 double-blind RCT, 44 patients with mildly-to-moderately active ulcerative colitis took aloe vera gel 100 mL or placebo twice daily for four weeks. Clinical response occurred in 47% on aloe versus 14% on placebo (p < 0.05) and histological activity fell, but the primary endpoint of clinical remission (30% vs 7%) did not reach significance ^{24Reference 24Langmead et al. · 2004RCTRandomized, double-blind, placebo-controlled trial of oral Aloe vera gel for active ulcerative colitisView study →}. It was well tolerated.

Gap: the single trial missed its primary remission endpoint, and no larger follow-up trial has been published.

In a 1991 in-vitro study, anthraquinones extracted from aloe (including aloe-emodin) inactivated enveloped viruses — herpes simplex, varicella-zoster, influenza and others — by disrupting the viral envelope ^{25Reference 25Sydiskis et al. · 1991In vitroInactivation of enveloped viruses by anthraquinones extracted from plants — in vitro studyView study →}.

These are latex constituents, the same stimulant-laxative anthraquinones that decolorized internal products remove, so the finding does not apply to the gel.

Gap: the activity is from isolated latex anthraquinones in cell culture; claims of activity against HIV trace to secondary sources rather than clinical data.

Whole-leaf extract. In a two-year US National Toxicology Program study, rats given non-decolorized whole-leaf Aloe barbadensis extract in their drinking water at 1% and 1.5% developed tumours of the large intestine; mice did not ^{26Reference 26Boudreau et al. · 2013AnimalClear evidence of carcinogenic activity by a whole-leaf extract of Aloe barbadensis miller (Aloe vera) in F344/N rats — 2-year rodent carcinogenicity studyView study →}. A follow-up analysis found those tumours share molecular pathways with human colorectal cancer ^{27Reference 27Pandiri et al. · 2011AnimalAloe vera non-decolorized whole-leaf extract-induced large intestinal tumors in F344 rats share molecular pathways with human sporadic colorectal tumors — animal modelView study →}. On this basis whole-leaf extract is classed as a possible human carcinogen (IARC Group 2B) ^{28Reference 28Guo et al. · 2016ReviewAloe vera — a review of toxicity and adverse clinical effectsView study →}. The finding does not describe the decolorized inner-leaf gel used in most internal products, but whole-leaf extracts are best avoided internally.

Latex and long-term laxative use. Prolonged internal use of the latex is associated with diarrhoea, low potassium, pseudomelanosis coli and, rarely, kidney failure ^{28Reference 28Guo et al. · 2016ReviewAloe vera — a review of toxicity and adverse clinical effectsView study →}. The EU monograph lists cramping abdominal pain and loose stools, and with long-term use water and electrolyte loss, protein and blood in the urine ^{53Reference 53European Medicines Agency · 2016ReviewEuropean Union herbal monograph on Aloe barbadensis Mill. and on Aloe (various species, mainly Aloe ferox Mill. and its hybrids), folii succus siccatus (EMA/HMPC/625788/2015) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-aloe-barbadensis-mill-and-aloe-various-species-mainly-aloe-ferox-mill-and-its-hybrids-folii-succus-siccatus_en.pdfView study →}. It limits the latex to one week, two or three doses in that week usually being enough ^{53Reference 53European Medicines Agency · 2016ReviewEuropean Union herbal monograph on Aloe barbadensis Mill. and on Aloe (various species, mainly Aloe ferox Mill. and its hybrids), folii succus siccatus (EMA/HMPC/625788/2015) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-aloe-barbadensis-mill-and-aloe-various-species-mainly-aloe-ferox-mill-and-its-hybrids-folii-succus-siccatus_en.pdfView study →}.

When the latex is not used. The EU monograph contraindicates it in bowel obstruction, appendicitis, inflammatory bowel disease such as Crohn’s disease or ulcerative colitis, abdominal pain of unknown cause and severe dehydration ^{53Reference 53European Medicines Agency · 2016ReviewEuropean Union herbal monograph on Aloe barbadensis Mill. and on Aloe (various species, mainly Aloe ferox Mill. and its hybrids), folii succus siccatus (EMA/HMPC/625788/2015) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-aloe-barbadensis-mill-and-aloe-various-species-mainly-aloe-ferox-mill-and-its-hybrids-folii-succus-siccatus_en.pdfView study →}. This applies to the latex, not to the inner-leaf gel tested in ulcerative colitis ^{24Reference 24Langmead et al. · 2004RCTRandomized, double-blind, placebo-controlled trial of oral Aloe vera gel for active ulcerative colitisView study →}.

Potassium-sensitive drugs. Low potassium from long-term latex use strengthens the effect of cardiac glycosides such as digoxin and interacts with antiarrhythmic drugs. Diuretics, corticosteroids and liquorice root add to the potassium loss, and the EU monograph asks people on these, or on QT-prolonging drugs, to see a doctor first ^{53Reference 53European Medicines Agency · 2016ReviewEuropean Union herbal monograph on Aloe barbadensis Mill. and on Aloe (various species, mainly Aloe ferox Mill. and its hybrids), folii succus siccatus (EMA/HMPC/625788/2015) — regulatory monograph. https://www.ema.europa.eu/en/documents/herbal-monograph/final-european-union-herbal-monograph-aloe-barbadensis-mill-and-aloe-various-species-mainly-aloe-ferox-mill-and-its-hybrids-folii-succus-siccatus_en.pdfView study →}.

Antidiabetic drugs. Oral gel modestly lowers fasting glucose and HbA1c in pooled trials, so it may add to glucose-lowering medicines ^{1,2Reference 1Zhang et al. · 2016Meta-analysisEfficacy of Aloe Vera supplementation on prediabetes and early non-treated diabetic patients — systematic review and meta-analysis of randomized controlled trialsView study →Reference 2Suksomboon et al. · 2016Meta-analysisEffect of Aloe vera on glycaemic control in prediabetes and type 2 diabetes — systematic review and meta-analysisView study →}.

Surgery. A 35-year-old woman lost 5 litres of blood during surgery on a large haemangioma after taking aloe tablets. The size and blood supply of the haemangioma were the main cause. The authors judged a combined antiplatelet effect of aloe and the anaesthetic sevoflurane a possible contributor, and advise stopping antiplatelet herbs before surgery ^{47Reference 47Lee A et al. · 2004Case reportPossible interaction between sevoflurane and Aloe vera — case reportView study →}.

Drug metabolism. No human pharmacokinetic interaction study of aloe has been done. In rats, single and repeated doses of aloe leaf juice lowered blood levels of cyclosporine, a drug handled by both P-glycoprotein and CYP3A4; aloe activated P-glycoprotein, and its metabolites activated CYP3A4, in laboratory tests ^{48Reference 48Yang MS et al. · 2017AnimalAloe activated P-glycoprotein and CYP 3A: a study on the serum kinetics of aloe and its interaction with cyclosporine in rats — ratView study →}. The latex anthraquinone aloe-emodin is itself broken down by CYP3A4 ^{49Reference 49Hu YH et al. · 2022In vitroInhibition of CYP3A4 enhances aloe-emodin induced hepatocyte injury — in vitroView study →}, and in a test-tube study it strongly inhibited CYP1B1, an enzyme that metabolises oestrogen ^{52Reference 52Meng X et al. · 2022In vitroThe isomers, aloe-emodin and emodin, possess differential inhibitory activities against CYP1B1 enzyme — in vitroView study →}. None of this has been confirmed in people.

Absorption of other drugs. A stimulant-laxative effect may reduce absorption of other oral medicines. In a gut-cell model, by contrast, the gel and whole-leaf extract loosened the junctions between cells and let a small marker molecule pass more easily ^{51Reference 51Haasbroek A et al. · 2019In vitroIntestinal Drug Absorption Enhancement by Aloe vera Gel and Whole Leaf Extract: In Vitro Investigations into the Mechanisms of Action — in vitroView study →}.

On the skin. The gel is well tolerated in the trial literature, including on irradiated and post-graft skin, with no infection signal ^{7,9,16Reference 7Huang et al. · 2024Meta-analysisEffects of Aloe vera on burn injuries — systematic review and meta-analysis of randomized controlled trialsView study →Reference 9Burusapat et al. · 2018Systematic reviewTopical Aloe vera gel for accelerated wound healing of split-thickness skin-graft donor sites — double-blind randomized controlled trial and systematic reviewView study →Reference 16Wang et al. · 2022Systematic reviewAloe vera for prevention of radiation-induced dermatitis — systematic review and cumulative analysis of randomized controlled trialsView study →}. Contact allergy is possible but uncommon.