Aloes resin

Free to every reader. The safety section of every monograph is open to everyone, signed in or not. In an emergency call 000. For poisoning, call the Poisons Information Centre on 13 11 26.

15. Safety

15.1 Adverse effects

Overdose. Griping pain and severe diarrhoea with fluid and electrolyte loss; treatment is supportive with generous fluids and monitoring of electrolytes, potassium above all, especially in older people [5,6]. Barnes adds nephritis, bloody diarrhoea and haemorrhagic gastritis at large doses [9].

15.2 Toxicology, genotoxicity and carcinogenicity

Genotoxicity. Aloes extracts were negative in bacterial mutation tests in most reports, positive in Salmonella TA1537 only at 5,000 µg/plate, and clastogenic in CHO cells at 3,000 to 4,000 µg/mL without metabolic activation; a mouse micronucleus test was negative [7]. Aloe-emodin and emodin were mutagenic or clastogenic in several in vitro systems, acting through topoisomerase II; in vivo tests of aloe-emodin (mouse micronucleus, rat chromosome aberration, mouse spot test, rat hepatocyte unscheduled DNA synthesis) were negative [7]. EFSA’s 2018 opinion reached a stricter view: aloe-emodin was genotoxic in vivo; aloe extracts were genotoxic in vitro, possibly because of their hydroxyanthracene content; and hydroxyanthracene derivatives should be treated as genotoxic and carcinogenic unless specific data show otherwise [24]. EFSA could not set a daily intake free of concern [24]. The two European bodies weighed the same kind of data differently; the question is open. An in vivo comet test of aloe-emodin published in 2021 (Galli and colleagues) is requested in full text and not assessed here.

Carcinogenicity. In the US National Toxicology Program’s 2-year drinking-water study, a non-decolourised whole-leaf extract of A. vera (aloin A 5.7 to 7.2 mg/g in the 2-year material) gave clear evidence of carcinogenic activity in male and female F344/N rats, with adenomas and carcinomas of the large intestine at 1.0 and 1.5 per cent; none were seen in controls. There was no evidence of carcinogenic activity in mice [22]. IARC classified whole-leaf extract of A. vera as possibly carcinogenic to humans (Group 2B): inadequate evidence in humans, sufficient in experimental animals [23]. The HMPC’s assessor noted that the extract was not specified by hydroxyanthracene content, so a dose relation cannot be drawn, but that the results add to the concern about anthraquinones [7]. A 2-year study of Aloe arborescens whole-leaf powder in rats found colon adenomas at 4 per cent of diet only, which the authors put down to diarrhoea-related irritation [7]. No carcinogenicity study of the dried exudate itself exists [6].

Human epidemiology (class data). As summarised by the HMPC: a retrospective endoscopy series (3,049 patients) and a prospective series (1,095) gave a relative risk of 3.04 (95 per cent CI 1.18 to 4.9) for colorectal cancer with chronic anthranoid laxative abuse (Siegers and colleagues 1993); the Melbourne Colorectal Cancer Study found no association (Kune 1993); a prospective case-control study (202 cancers, 114 adenomas, 238 controls) found odds ratios of 1.0 for both (Nusko and colleagues 2000); a meta-analysis of 14 case-control studies gave pooled odds ratios of 1.48 for constipation and 1.46 for cathartic use, which the authors attributed to diet (Sonnenberg and colleagues 1993) [7]. The HMPC concluded that the question of a carcinogenic risk from long-term anthranoid laxatives "is still open" [7]. The full texts of the Siegers and Nusko papers are requested.

Reproductive toxicity. No teratogenic or fetotoxic effects in rats given aloe extract up to 1,000 mg/kg or aloin A up to 200 mg/kg [5]. The HMPC relates the reproductive findings to maternal toxicity from diarrhoea [6,7].

15.3 Contraindications

15.4 Herb–drug interactions

No pharmacokinetic interaction study of aloes resin was found; the HMPC found none [7].

15.5 Populations

Pregnancy and lactation: contraindicated (15.3). Children: not under 12 years; see 15.3; no clinical data [7]. Older people: electrolyte monitoring matters most, and weakness and orthostatic hypotension may be worse with repeated use [5,6]. Kidney disease: electrolyte imbalance [6]. People taking digoxin, antiarrhythmics, diuretics or corticosteroids: see 15.4; a potassium check is worth making if aloes is taken for more than a few doses.

15.6 Australian regulatory safety position

The Permissible Ingredients Determination requires, for an oral medicine whose maximum daily dose supplies more than 10 mg of hydroxyanthracene derivatives, the statements "Use in children under 12 years is not recommended" (CHILD3) and "Prolonged use may cause serious bowel problems" (LAX2), and statement LAX3, which warns against use with abdominal pain, nausea, vomiting or diarrhoea and carries a pregnancy and breastfeeding advisory; "Drink plenty of water" (LAX1) when marketed as a laxative; and, when not marketed as a laxative, statements naming the herb and warning that the product may have a laxative effect [3]. Aloes is not scheduled in the Poisons Standard; danthron (1,8-dihydroxyanthraquinone), a synthetic relative, is Schedule 4 for human use [12].

TGA safety alerts, recalls and adverse event reports. The TGA website was searched in September 2026 for aloe with safety alert, advisory, recall and Medicines Safety Update. No safety alert, advisory or Medicines Safety Update item on aloes or on aloe-containing oral laxatives was found. Two Class II consumer-level recalls in 2006 (TGA references R2005/1702-4 and RN-2006-0010) concerned topical aloe vera gel, cream and spray products that may have been contaminated with bacteria; they do not bear on the dried exudate [30]. One aloe-containing oral laxative, Nulax Fruit Laxative with Aloe and Flaxseed (ARTG 299196), is listed among the TGA’s cancellations by sponsors, cancelled under section 30(1)(c) of the Therapeutic Goods Act 1989 with effect from 27/06/2024; no safety reason is published [30]. The Database of Adverse Event Notifications could not be searched: its public search sits behind an interactive terms-of-use page that refused automated access in September 2026. It is to be searched by hand before version 1.1 (section 20).

Referral. Anyone thinking of using aloes, and anyone who needs a laxative for more than a few days, should consult a degree-qualified herbalist with competencies and adequate training in pharmacognosy. A change in bowel habit, blood in the stool, or pain, nausea or vomiting needs assessment before any laxative is taken; so does rectal bleeding, or no bowel movement within 24 hours of a laxative dose [5,6].