Bilberry (Vaccinium myrtillus)

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15. Safety

Adverse effects in trials and surveillance (uncontrolled human data and trial safety reports). Bone and Mills and Barnes report a post-marketing surveillance study of the Italian extract in 2,295 patients, which Barnes describes as unpublished, most taking the equivalent of 115 mg anthocyanins a day for 30 to 60 days: 94 (4.1 per cent) reported mild effects, mainly gastrointestinal (gastric pain, heartburn, nausea, 3.3 per cent), and a few skin or nervous-system effects (0.2 per cent each) [7,8]. Ozawa reported no severe adverse event in either arm [25]; Aboufarrag reported no serious adverse event [28]; in the colitis trial serious adverse events were rare, the commonest adverse events were stool discolouration and headache, and the authors saw no pattern suggesting toxicity [26]. In the open colitis pilot a third of patients reported mild to moderate flatulence [6]. Whole fresh fruit may irritate the gut of sensitive people because of its fibre and acids [7].

Toxicology (animal and in vitro data). Oral LD50 of the extract in mice and rats is above 2 g/kg; a single 3 g/kg dose in dogs caused only dark urine and faeces [6,8]. Six months of 125–500 mg/kg in rats and 80–320 mg/kg in dogs produced no toxic effect [6,8]. Bone and Mills report no mutagenicity for the standardised extract in vitro or in rats at up to 5 g/kg, and weak Ames activity for one bilberry extract attributed to quercetin [7]; the HMPC notes that the weak Ames result came from a leaf extract [6]. The HMPC judged the toxicology "limited", the reproductive and genotoxicity tests "almost 50 years" old and below current standards, and declined an EU list entry for lack of genotoxicity data [6].

How the safety statements are graded. Each statement below carries the kind of evidence behind it, from strongest to weakest: controlled human data; uncontrolled human data (open studies, surveillance); human case reports; animal data; theoretical (mechanism or a manufacturer’s or regulator’s precaution without human cases). No statement in this section rests on a controlled trial designed to test safety.

Contraindications. Hypersensitivity to bilberry [4,5] (regulatory precaution, theoretical: no case of allergy to bilberry fruit is described in the sources read). Bone and Mills list none [7].

Interactions.

Co-use is common: in Norwegian general practice bilberry was the herbal product most often taken daily with prescribed drugs, and almost 40 per cent of patients on anticoagulants used garlic and bilberry; only half had told their prescriber (Djuv 2013, as reported by the HMPC) [6].

Pregnancy and lactation. The sources disagree, and this should be said plainly.

AIP reading: the fruit as food and as a traditional decoction is not a concern; a concentrated extract taken for weeks in pregnancy has no controlled safety data. Anyone pregnant or breastfeeding who is considering an extract should consult a degree-qualified herbalist with competencies and adequate training in pharmacognosy.

Children and older people. The EU monographs do not recommend the dried fruit under 12 years or the extract under 18 years, for lack of data [4,5] (theoretical). The HMPC assessment report advises against use under 6 years, and notes that German product information contraindicates the tea under 2 years [6] (theoretical). Bone and Mills note that concentrated bilberry powder was well tolerated in infants with dyspepsia [7]. Older people on anticoagulants are the group in the case reports [6].

Overdose. No case reported [4,5,7].

Leaf and adulterant hazards. Barnes reports that chronic doses of the leaf at 1.5 g/kg or more have been fatal in animals [8]. That does not apply to the fruit, but it is one more reason to check that fruit products are fruit. A dye-adulterated extract (section 10) exposes the patient to an undeclared synthetic colour.

TGA. Searched in September 2026.

• Safety alerts. No TGA safety alert, advisory or recall names bilberry or Vaccinium myrtillus. A search of the TGA website for "bilberry" returned 178 items, all of them ARTG entries, cancellations, and consents under section 14 of the Therapeutic Goods Act 1989. The consents concern label wording for other ingredients in bilberry combination products. One regulatory cancellation, of Mothernest Eye Smart – Bilberry with Lutein (ARTG 223641) on 11/07/2016, was made because the goods had changed from those listed and did not conform to an applicable standard; no safety reason was given [46].
• Database of Adverse Event Notifications (DAEN), medicines. Data to 16/09/2026. A search for "bilberr" found 5 reports naming a bilberry product as a suspected medicine, 1999 to 2026, with no deaths: face oedema, pain and pruritus (1999); acute kidney injury with N-acetylcysteine and ascorbic acid also suspected (2018); vulvovaginal burning (2024); headache (2026); dyspnoea and throat tightness (2026). A search for "myrtillus" found 208 reports for any product containing the plant, mostly multivitamins, with 1 death; the commonest reaction terms were nausea and vitamin B6 toxicity, which point to other ingredients. None of the 5 bilberry-named reports, and none of the 20 commonest reaction terms in the larger set, concerns bleeding or a changed INR. The DAEN interface would not apply a reaction filter to the larger set, so a bleeding report hidden in it has not been ruled out [47]. DAEN reports are unverified and do not establish cause.

Grade: spontaneous reports (uncontrolled human data). The Australian record adds no new safety signal. The two allergic-type reports (1999 and 2026) are consistent with the hypersensitivity contraindication.

Warning signs. The EU extract monograph lists skin inflammation, thrombophlebitis, hardening under the skin, severe pain, ulcers, sudden swelling of one or both legs, and heart or kidney failure as reasons to stop self-treatment of heavy legs and get assessed, and sets a 2-week limit on symptoms that persist [5]; the dried-fruit monograph sets a 3-day limit on self-treating diarrhoea [4]. Sudden swelling of one leg can mean a deep-vein thrombosis, and bloody diarrhoea, fever or dehydration need urgent medical assessment. These are outside the scope of a herbal remedy.