SEARCH

SEARCH BY CITATION

Summary

  1. Top of page
  2. Summary
  3. Review criteria
  4. Introduction
  5. Method
  6. Results
  7. Discussion
  8. Acknowledgements
  9. Reference
  10. Appendix

Aim:  The aim of this systematic review was to critically evaluate the evidence regarding the adverse effects (AEs) of homeopathy.

Method:  Five electronic databases were searched to identify all relevant case reports and case series.

Results:  In total, 38 primary reports met our inclusion criteria. Of those, 30 pertained to direct AEs of homeopathic remedies; and eight were related to AEs caused by the substitution of conventional medicine with homeopathy. The total number of patients who experienced AEs of homeopathy amounted to 1159. Overall, AEs ranged from mild-to-severe and included four fatalities. The most common AEs were allergic reactions and intoxications. Rhus toxidendron was the most frequently implicated homeopathic remedy.

Conclusion:  Homeopathy has the potential to harm patients and consumers in both direct and indirect ways. Clinicians should be aware of its risks and advise their patients accordingly.


Review criteria

  1. Top of page
  2. Summary
  3. Review criteria
  4. Introduction
  5. Method
  6. Results
  7. Discussion
  8. Acknowledgements
  9. Reference
  10. Appendix

We included all case reports and case series of homeopathic remedies to treat human patients suffering from any type of clinical condition using 5 databases from their inception to January 2012, without language restrictions.

Message for the clinic

Homeopathy is one of the most commonly used type of complementary medicine. It is utilized for a wide variety of clinical conditions. Its safety has not been critically evaluated so far. The current evidence shows that homeopathy is not as innocent as it seems. It sometimes can lead to serious adverse events.

Introduction

  1. Top of page
  2. Summary
  3. Review criteria
  4. Introduction
  5. Method
  6. Results
  7. Discussion
  8. Acknowledgements
  9. Reference
  10. Appendix

Homeopathy can be defined as ‘a therapeutic method that often uses highly diluted preparations of substances whose effects when administered to healthy subjects correspond to the manifestation of the disorder (symptoms, clinical signs and pathological states) in the unwell patient’ (1). It is one of the most popular form of complementary and alternative medicine in the UK and elsewhere (2). The reasons for this widespread use are probably complex, but the assumption that homeopathy is safe is certainly an important factor (1).

Although most homeopathic remedies are highly diluted, direct adverse effects (AEs) have been reported (3). Indirect risks mainly relate to replacing effective conventional treatments with ineffective homeopathic preparations (3,4).

The aim of this systematic review was to provide a summary and critical evaluation of the published evidence regarding direct and indirect AEs associated with homeopathy.

Method

  1. Top of page
  2. Summary
  3. Review criteria
  4. Introduction
  5. Method
  6. Results
  7. Discussion
  8. Acknowledgements
  9. Reference
  10. Appendix

Electronic literature searches were conducted in January 2012 to identify case series (CS) and case reports (CR) of AEs associated with homeopathy in human patients. The following electronic databases were used: MEDLINE, EMBASE, AMED, CINHAL and ISI. Details of the search strategy are presented in the Appendix. In addition, our own extensive department files were hand-searched for further articles.

No restrictions of language or time of publication were imposed. To be included, CS or CR had to pertain to AEs associated with the use of any type of homeopathic treatment in human patients. Data from spontaneous reporting systems were included as well. We also included reports where harm was not because of a homeopathic remedy, but was associated with the use of homeopathy as a replacement of conventional treatments. Information from the included CS or CRs were extracted according to predefined criteria and assessed by two independent reviewers. Causality was estimated based on the description provided by the authors of the primary articles. Any disagreements were settled through discussion.

Results

  1. Top of page
  2. Summary
  3. Review criteria
  4. Introduction
  5. Method
  6. Results
  7. Discussion
  8. Acknowledgements
  9. Reference
  10. Appendix

Our searches generated 378 articles, of which 340 had to be excluded (Figure 1). Thus, 35 reports met our eligibility criteria (5–40). Table 1 summarises direct AEs associated with the use of homeopathy. Table 2 presents indirect AEs related to the substitution of conventional care with homeopathy.

image

Figure 1.  Flow diagram

Download figure to PowerPoint

Table 1.   Case series and case reports of AEs directly related to homeopathy
Author (year) (Reference)Study designNumber of patientsHomeopathic remedy (potency)Concomitant treatmentAdverse eventPossible explanationCausalityTreatment/clinical outcome
  1. AEs, adverse effects; ALTE, apparent life-threatening event; DRESS, drug rash with eosinophilia and systemic symptoms; ECG, electrocardiogram; EEG, electroencephalogram; ICU, intensive care unit; NFI, no further information; n.r., not reported; SB, sinus bradycardia; TdP, torsades de pointes; VF, ventricular fibrillation; C, case.

  2. *As judged by the author of primary report.

  3. †As judged by the present author.

Aberer (1991) (5)Case series3C.1. Peruvian bark and Ipecacuanha (D4) C.2. Unspecified slenderness drops (n.m.) C.3. Unspecified mixture of grass pollen (n.m.)n.m.C.1. Pruritus, swelling and erythroderma C.2. Morbiliform and pruritic rash C.3. AnaphylaxisAllergic reactions*Almost certainC1 – Anti-histamines. NFI. C2 – Hospital admission. NFI C3 – ICU admission. Adrenaline, steroids and intravenous fluid supplementation. NFI
Audicana (2001) (6)Case report1Mercurius Heel®S containing Mercurius solubilis Hahnemanni (D10), Hepar sulfuris (D8), Lachesis (D12), Phytolacca (D4), Ailanthus glandulosa (D3), Echinacea angustifolia (D3), Belladonna (D4)MerbrominWidespread maculopapular vesicular rashAllergic reaction/mercury intoxication*Almost certainSystemic corticosteroids and antihistamines Post-inflammatory hypopigmentation remained
Aviner (2010) (7)Case series11Gali-col Baby containing Phosphorica, bryonia, Nux-vomica, Cuprum metallicum and Veratrum album (n.m.)n.m.ALTE including apnoea, cyanosis, regurgitation, flaccidity or vomitingOverdosing, toxicity*Almost certainHospital admission. Lumbar puncture, lactate, ammonia, ECG, EEG, brain sonography, gastrografin imaging, and echocardiogram. All fully recovered within 13 days
Barquero,Romero (2004) (8)Case report1 Nux vomica and Rhus tox (n.m.)GlimepirideAcute pancreatitis, necrosis of the pancreatic headUnclear†LikelyICU admission. Respiratory distress, gastrointestinal bleeding and death after 2 weeks
Bernez (2008) (10)Case report1Sedativ PC (6 ingredients in 6CH)n.m.DRESS syndrome, severe pulmonary involvementHypersensitivity*CertainFull recovery
Cardinali (2004) (11)Case report11. Rhus Toxicodendron mother tincture (alcohol solution) 2. Rhus Toxicodendron (7CH)n.m.Widespread dermatitis, leukocytosisAllergic reaction*CertainFull recovery
Chakraborti (2003) (12)Case series3C.1.& C.3. Arsenic Bromide 1-X (n.m.) C.2. Arsenicum Sulfuratum Flavum-1-X (n.m.)n.m.C.1. Melanosis and keratosis, C.2. Skin lesions C.3.Acute gastrointestinal illness, leukopaenia, thrombocytopaenia and diffuse dermal melanosisArsenic intoxication*Almost certainC1-C2 – Improvement on discontinuation C3 – Toxic polyneuropathy and quadriparesis
Curry (2006) (14)Case report1Caesium chloride (n.m.)Chemotherapy, anaesthetic agents, CoQ10, coral calcium, bovine colostrum, seal oil, multivitamin, vitamin D, Cardiac arrestCesium intoxication* or interactions with anaesthetic agents†LikelyFull recovery. NFI
Duque-Estrada (2009) (16)Case series1Injection of Lilium compositum, Solanum compositum, Thuja, and Tanacetum (n.m.)n.m.Hair lossUnclear*Almost certainComplete recovery after 7 months
Farrell (1995) (18) Case report1Oral Hypericum perforatuma and Ledum palustre (n.m.)NoneSevere acute tubulointerstinal nephritisUnclear†LikelyHospital admission. Hemodialysis and methylprednisone. Improved renal function after 14 days
Forsman (1991) (19)Case series2C.1. a. AKO-PLEX containing: Juglans (D6), Silicea (D12), Antimonium (D12), Arnica (D6), Sarsaparilla (D6), Daisies (D6), Mezereum (D6), Dulcamara (D6) b. Forte Saponaria containing: Gramin jugul., Rhamnus cath., Viola od., Cichor., Cent., Inula, Nastur., Sapon., Scroph. Bellis, Viola tr., Dulcam, Hydrocot, Mezer, Sarsap, Thuja (all at D6) c. OT 10 containing: Sennae, Frangula, Phaseoli, Mentha pip., Rubi, Fucus, Malvae, Taraxacum, Betula alba. C.2. Three different unspecified preparations (n.m.)n.m.C.1. Atopic dermatitis C.2. Severe swelling, bleeding and rashesAllergic reaction*Likely in both casesC1 – Hospital admission. Topical steroids and antihistamines. Full recovery within several months. C2 – Hospital admission. NFI
Geukens (2001)(20)Case report1 Aconitum 1000, Baryta carbonica, Cantharis 1000,Gambogia, Pulsatilla, Rhus tox (M and 10 M) n.m.Heart disease and bladder cancerUnclear†Almost certainRadiotherapy. Full recovery
Goodyear (1990) (21)Case report1Nine different remedies, including iron and arsenic (both at 6 °C) n.m.Hyponatraemia, hypoalbuminaemia, erythaema and limb oedemaUnclear*Almost certainHospital admission. Sodium chloride solution, albumin infusions, intravenous flucloxacillin and benzylpenicillin, potassium permanganate baths, topical corticosteroids and antibiotics. Persistent mild eczema at 4 months follow up
Guha (1999) (22) Case report1Tincture of aconiten.m.Severe bradycardia, reversible panconduction defect, hypotension and syncopeAconitum intoxication*Almost certainMarked improvement in symptoms within a few hours
Kerr (1986) (24)Case report1Regeneration Tablets- a mixture of 19 ingredients (n.m.)n.m.Pancreatitis, pain, nausea, vomitingProtoanemonin and saponic glycosides toxicity†Almost certainHospital admission. Conservative treatment. Full recovery after 6 days
Kuenzli (2004) (25)Case report1Topical and/or oral calcium, sulphur, lycopodium, mercurius, cantharis, rhus toxicodendron, calcium carbonicum, sepia and tuberculinum (n.m.)NoneBullous pemphigoid, severe asthaeniaMercury intoxication*LikelyOral prednisone and sulfapyridine. Rapid improvement within 2 weeks
Menniti-Ippolito (2008) (27)Case series21Various remedies-both mono and poly-preparations, including Kalium Bichromicum and Mercurius Sublimatus Corrosivus (from D1)n.m.Allergic reactionsImmune allergic reactions, hypersensitivity†Likelyn.r.
Monk (1986) (28)Case report1Injection of Nat Mur 200 (n.m.)n.m.Acute erythrodermaUnknown*LikelyICU admission. n.r.
Montoya- Cabrera (1991) (29)Case report1Mercurius 6a (D6)n.m.Dermatitis, irritability and albuminuriaMercury intoxication*Almost certainD-penicillamine administration. Full recovery
Mortelmans (2004) (30)Case report1Loco X112 drops (n.m.)Alcohol and amphetamineExtreme agitationInteractions of alcohol, thyroid extract free T3 and T4), diethylpropione, and amphetamine * and†LikelyDiazepam, propofol. Full recovery
Potier (1998) (31)Case report1Unspecified remedies (n.m.)n.m. but patients with history of depression, cholecystectomy, neurological and vascularaccidents.ComaBromate intoxication*LikelyAntibiotics, mucolytics and haemodialysis. Full recovery within 15 days
Prasad (2006) (32)Case report1Unspecified remedy (n.m.)n.m. but patient with a history of neck swelling, cough, haemoptysis, shortness of breath, fever and weight lossArsenical keratosis and cancerArsenic intoxication*LikelyHospital admission. Chemotherapy. Death
Rodriguez-Vico (2009) (33)Case report1Petroleum (D5)CarbamazepineTachypnoea, high fever, lower limb areflexia, hypotension, pupillary abnormalities, gait ataxia, cognitive-behavioural disordersKerosene intoxication*Almost certainHospital admission. Full recovery within 1-week
Sasseville (1995) (34)Case series2C.1. Ointment containing Rhus toxicodendron (2CH), Rhododendron ferrugineum (2 CH), Ruta graveolens (2 CH), Ledum palustre (2 CH) C.2. Ointment containing Rhus toxicodendron tincture 4.00 gHistory of dermatitisAllergic dermatitis, perioral swelling and vesiculationAllergic reactions*LikelyC1 – Clobetasol 17-propionate. Full recovery within 2 weeks C2 – Oral corticosteroids. Full recovery within 5 days
Stevens (1978) (35)Case report1Unspecified remedy (n.m.)NoneMigraine, retrosternal oppression, paresthesias, pain, burning sensation,Thall intoxication*LikelyPrussian blue and potassium chloride. Full recovery within 1-week
Turkoglu-Raach (2010) (36)Case report1Notakehl® containing Penicillium chrysogenum (D4)n.m.Renal failure with metabolic acidosis, interstitial nephritis and hyperkalaemiaAllergic reaction*and†LikelyCorticosteroids and hemodialysis. Full recovery
Van Ulsen (1988) (37)Case report1Pentackan Sinnabaum (D4)n.m.Severe exacerbation of eczaema with swellingChromium intoxication*LikelyNo improvement.
Von Mach (2006) (38)Case series1070Unspecified remedies (n.m.)n.m.Mostly mild symptoms (no details provided)Unclear*Unclearn.r.
Wille (2010) (39)Case report1Xylitol containing homeopathic globulesn.m.Severe metabolic acidosis, weight loss, chronic diarrhoeaEnteral bicarbonate loss*LikelyICU admission. Full recovery after 3 months
Zuzak (2010) (40)Case series9C.1.–C.2. Calendula officinalis (mother tincture) C.3. Mater perlarum (D4) C.4. Allium cepa (D4–D15) C.5.–C.6. Chamomile globules (n.m.) C.7. Bach flower rescue drops (n.m.) C.8. Chamomilla (D10), Mercurius (D15), sulphur (D12) C.9. Thujas (mother tincture)n.m.C.1. Sneezing, rhinitis; C.2. Slight lethargy; C.3. Emesis; C.4. euphoria; C.5. Abdominal pain, flatulence; C.6. Emesis; C.7.Problem with balance, somnolence; C.8. Pain; C.9. Burning lips, nausea, emesisUnclear*Likely in all casesn.r.
Table 2.   Case series and case reports of AEs related to substitution of conventional care with homeopathy
Author (year) (Reference)Study designNumber of patientsHomeopathic remedy (potency)Concomitant treatmentConditionPossible explanationCausalityTreatment/clinical outcome
  1. AEs, adverse effects; ICU, intensive care unit; CT, conventional treatment; NFI, no further information; n.m., not mentioned; C, case.

  2. *The most commonly used.

  3. †As judged by the author of primary report.

  4. ‡As judged by the present author.

Benmeir (1991) (9)Case report1Ointment and unspecified remedies (n.m.)n.m.Malignant melanomaNegligence and lack of CT†,‡CertainSurgery. Full recovery after 7 months
Colin (2006) (13)Case series2 Lycopodium, Pulsatilla and Sulphur*(CH 15 and 30)n.m.Deterioration of pulmonary allergyUnclear‡Likelyn.r.
Delaunay (2000)(15)Case report1 Ledum palustre (5CH) and Malaria officinalis (4 CH)Conventional prophylactic drugs, NFIMultiple organ system failureParasitaemia†CertainICU admission. Intensive care for 2 months. NFI
Edelson (1999) (17)Case report1Unspecified remedy (n.m.)n.m.Deterioration of sarcoidosisDiscontinuation of CT†Almost certainHospital admission. Corticosteroids. NFI
Forsman (1991) (19)Case report1Unspecified ointmentn.m.Malignant melanomaDelayed diagnosis‡LikelyUnknown
Ibsen (1987) (23)Case series4Unspecified remedies (n.m.)n.m.C.1.–C.4. Severe aggravation of atopic dermatitisDiscontinuation of CT‡LikelyICU admission. Full recovery
Lim (2011) (41)Case series3Unspecified remedies (n.m.)n.m.C.1. Malnutrition, sepsis and death C.2. Malnutrition and oedema C.3. SeizuresNegligence and lack of CT†, ‡CertainHospital admission. NFI
Luder (2000) (26)Case series3Unspecified remedies (n.m.)n.m.C.1. Pneumococcal pneumonia with purulent pericarditis and coma C.2. Glomerulonephritis, hypertensive heart failure and encephalopathy C.3. haemophilus influenzae meningitis, septicaemia high fever and seizuresNegligence and lack of CT†, ‡CertainC.1.Death C.2. Permanent hypertension C.3. Hydrocephalus and neuro-surgical drainage

The total number of patients amounted to 1159 (of those 1142 AEs were classified as direct and 17 as indirect AEs). The included articles originated from Austria, (5) Belgium, (20,31) Brazil, (16) Denmark, (23) France, (10,13,15) Germany, (36,38,40) Holland, (37) India, (32) Ireland, (18) Israel, (9,17,26) Italy, (11) Mexico, (29) Spain, (6,8,33) Sweden,(19) Switzerland, (25,39) UK(21,28) and the US (14,22,24). They were published between 1978 and 2010.

The implicated homeopathic remedies included Aconitum 1000, AKO-PLEX, Arsenic Bromide 1-X, Arsenicum Sulfuratum Flavum-1-X, Baryta carbonica, BHI Regeneration Tablets, calcium carbonicum, Cantharis 1000, caesium chloride, chromium, Forte Saponaria, Gambogia, Gali-col Baby, hypericum perforatuma, Ipecacuanha, iron, Kalium Bichromicum, Ledum Palustre, Lilium Compositum, Loco X112, Lycopodium, Malaria Officinalis, Mercurius Heel®S, Mercurius 6a, Mercurius Sublimatus Corrosivus, Nat Mur 200, Notakehl, Nux Vomica, OT-10 and Penicillium Chrysogenum, Pentackan Sinnabaum, Petroleum D-5, Peruvian bark, Pulsatilla, Rhododendron Ferrugineum, Rhus Toxicodendron, Ruta Graveolens, Sedativ PC, Slenderness Drops, Solanum Compositum, sulphur, tanacetum, thuja, tuberculinum or unspecified homeopathic remedies.

Direct AEs included abdominal pain, flatulence, acute erythroderma, acute pancreatitis, severe allergic reactions, atopic dermatitis, burning lips, nausea, emesis, apnoea, cyanosis, regurgitation, anaphylaxis, arsenical keratosis and cancer, bladder cancer, bullous pemphigoid, severe asthenia, cardiac arrest, cognitive-behavioural disorders, coma, death, dermatitis, severe pulmonary involvement, emesis, euphoria, extreme agitation, hyponatraemia and hypoalbuminaemia, erythaema, limb oedema, irritability and albuminuria, melanosis and keratosis, skin lesions, acute gastrointestinal illness, leukopaenia, thrombocytopaenia, diffuse dermal melanosis, metabolic acidosis, weight loss, chronic diarrhoea, morbiliform and pruritic rash with hospital admission, multiple alopecia and hair loss, pain, pancreatitis, problem with balance, somnolence, pruritus, swelling and erythroderma, renal failure with metabolic acidosis, interstitial nephritis and hyperkalaemia, severe acute tubulointerstinal nephritis, severe bradycardia, reversible panconduction defect, hypotension and syncope, severe swelling, bleeding, rashes, sneezing, rhinitis, slight lethargy, symptoms of thall poisoning, tachypnea, high fever, lower limb areflexia, hypotension, pupillary abnormalities, gait ataxia, widespread leukocytosis and widespread maculopapular vesicular rash. Direct AEs of homeopathy occasionally resulted in serious outcomes including cancer, death, dialysis, toxic polyneuropathy and quadriparesis. In several instances, patients presenting AEs required hospital admission (7,14,18,19,24) and pharmacotherapy (5,18,29,35,36).

Indirect AEs included deterioration of pulmonary allergy, deterioration of sarcoidosis glomerulonephritis, hypertensive heart failure and encephalopathy, haemophilus influenzae meningitis, septicaemia high fever and seizures, malignant melanoma, multiple organ system failure, oedema, pneumococcal pneumonia with purulent pericarditis and coma, sepsis and death and severe aggravation of atopic dermatitis. Indirect AEs of homeopathy resulted in the following clinical outcomes: death, permanent hypertension, hydrocephalus and the need for neuro-surgical drainage.

The duration of AEs ranged from a few hours (22) to 7 months (9,16). Eighteen patients experienced a full recovery (6,7,9–12,14,16,18,21–25,29–31,33,35,36,39) and four died (8,26,32,41). In six cases, details of AEs were insufficient for a judgment regarding cause and effect (13,19,27,28,34,37,38,40). In 17 cases, causality was deemed to be likely, certain in six, almost certain in 12 and unclear in one. The AEs were caused by allergic reactions, (5,6,8,11,19,27,34,36,39) ingestion of toxic substances (6,7,12,21,22,24,25,29–33,35,37) and substitution of conventional care (9,13,15,17,19,23,26,41).

Discussion

  1. Top of page
  2. Summary
  3. Review criteria
  4. Introduction
  5. Method
  6. Results
  7. Discussion
  8. Acknowledgements
  9. Reference
  10. Appendix

Our systematic review was aimed at summarising and critically evaluating the available evidence from CS and CR regarding AEs of homeopathy in human patients. According to our findings, homeopathy can lead to AEs, some of which are serious. A recent report on the safety of homeopathy by the European Council for Classical Homeopathy (ECCH) concluded that homeopathy is ‘safe to use’. However, this report was incomplete and included only a third of the CRs/CS located by us for the present review (42). The ECCH-report also commented on the safety of homeopathy relative to conventional treatments. It seems likely that homeopathic remedies cause far less and fewer AEs than conventional drugs, however, such a comparison might be misleading as not the absolute risk of an intervention, but its risk-benefit balance would determine the value of any medical treatment. If the benefit is small or non-existent, even a minute risk would tilt this balance into the negative.

An audit of the Bristol Homeopathic Hospital among 116 patients reported that 11% of them experienced AEs, including headaches, lethargy or vomiting (43). This percentage figure is difficult to interpret as the authors categorise diarrhoea, eczaema, gastrointestinal upset, hair loss, infections, nausea, migraines, pains, rash, skin irritation, tension headaches, tiredness/fatigue as ‘homeopathic aggravations’, new symptoms and/or return of old symptoms. Our own review of the evidence for or against the existence of homeopathic aggravations included 24 placebo-controlled trials reporting aggravations, and we came to the conclusion that ‘this systematic review does not provide clear evidence that homeopathic aggravations exist’ (44).

In the majority of cases, the possible mechanism of action involved allergic reactions or ingestion of toxic substances. Preparations of heavy metals, such as arsenic, cadmium, mercury or iron, which are frequently used in homeopathy can be toxic, (45) if not highly diluted. Other poisons regularly employed in homeopathy include aconitum, kerosene or thallium, which also can lead to serious health problems in sufficiently low dilutions.

We identified both direct and indirect AEs of homeopathy. The former related to the homeopathic remedy itself and the latter predominantly referred to the replacement of effective conventional therapies with ineffective homeopathic remedies. It was often impossible to distinguish precisely between the two types of AEs. The information whether a fully qualified and registered homeopath applied, the homeopathic remedy was frequently missing. Similarly, other valuable details were often not included in the primary publications. In 94.7% of cases, the potencies were described as below 12 °C, the point beyond which the likelihood of a single molecule being present in the remedy approaches zero. It is plausible that low dilutions of homeopathic preparations cause direct AEs, particularly allergic reactions. One might argue that incidences classified as indirect AEs by us are not truly AEs of homeopathy, but are the result of less than competent healthcare. We have therefore tried to differentiate as clearly as possible between the two. One might also wonder why relatively few indirect AEs have been reported. Most experts view the use of ineffective homeopathic treatments for serious conditions is potentially more harmful than the harm done by homeopathic remedies. One explanation could be that indirect harm of this nature rarely gets reported.Evidence of indirect AEs highlight the need for all homeopaths to be adequately trained such that harm of this nature can be avoided in future.

The preference of homeopathy over conventional medicine when dealing with serious, life-threatening conditions may cause serious harm, and this issue relates to the question of practitioner training (15,17,26). The treatment of cervical streptococcal lymphadenitis, acute lymphatic leukaemia, bacterial pneumonia and atopic dermatitis with homeopathic remedies is clearly dangerous (4,26,46) simply because homeopathy is not effective for any of these conditions. Other examples of serious conditions that have been treated homeopathically include anxiety, (47) depression, (48) eczema, (49) insomnia, (50) migraine prophylaxis and rheumatic conditions (51). The fact that such cases are being reported, albeit rarely, seems worrying. Again, we would therefore stress the need for making sure all homeopaths are medically competent.

We were unable to extract the data from one article that combined homeopathy with other modalities, such as herbals and dietary supplements. e.g. (52); in this retrospective analysis of cases, homeopathy had the second highest hospitalisation index with a total of 255 AEs reported.

Our systematic review has several strengths; we conducted extensive literature searches, did not impose restrictions according to language or time of publication, assessed the reported cases according to predefined criteria and tried to exclude bias where we could. We were able to include more AEs than any previous review has done. However, our systematic review also has a number of important limitations. They pertain to the potential incompleteness of the evidence. AEs of homeopathy are likely to be underreported; therefore, the number of cases summarised herein is less meaningful than the fact that such incidents exist at all. The often low quality of the primary reports further limits the conclusiveness of our findings. Several reports lacked sufficient detail, which renders the interpretation of their findings problematic (13,15,23,27,28,34,37,38,40). Given such caveats, a cause-effect relationship between the homeopathy and the AEs was frequently difficult to establish. We did not include systematic reviews, clinical trials, surveys and cohort studies in our review.A systematic review of the AEs of homeopathy, concluded that the incidence of AEs of homeopathic remedies was greater than that of placebo in controlled clinical trials; AEs included headache, tiredness, skin eruptions, dizziness, bowel dysfunctions and allergic reactions (53). Our review of CR and CS is thus not comprehensive. Crucially, it does not tell us anything about the incidence of AEs. Considering the widespread use of homeopathy worldwide and the relative paucity of the reported AEs, it might be very low. Collectively, these limitations render our review less conclusive than we had hoped.

In conclusion, several reports of AEs of homeopathy have been published and some AEs had serious consequences. Clinicians should be aware of the risks associated with homeopathy.

Acknowledgements

  1. Top of page
  2. Summary
  3. Review criteria
  4. Introduction
  5. Method
  6. Results
  7. Discussion
  8. Acknowledgements
  9. Reference
  10. Appendix

PP has a fellowship from the Royal College of Physicians, London. The RCP had no role in study design, data collection and interpretation. PP would like to thank Professor Yori Gidron for his translation of the Hebrew article.

Reference

  1. Top of page
  2. Summary
  3. Review criteria
  4. Introduction
  5. Method
  6. Results
  7. Discussion
  8. Acknowledgements
  9. Reference
  10. Appendix

Appendix

  1. Top of page
  2. Summary
  3. Review criteria
  4. Introduction
  5. Method
  6. Results
  7. Discussion
  8. Acknowledgements
  9. Reference
  10. Appendix

Appendix:

Detailed search strategy for medline

1 (homeop$ or homeop$ or homoop$).ti,ab,tw
2 Exp Homeopathy
3 (adrs or adr or complicat$ or aggravat$ or exacerbat$).ti,ab
4 (safe or safety or risk$ or harm$).ti,ab
5 Side effect$.ti,ab
6 (Adverse ADJ3 (effect$ or event$ or interaction$ or outcome$ or reaction$ or response$)).ti,ab
7 (Undesir$ ADJ3 (effect$ or event$ or interaction$ or outcome$ or reaction$ or response$)).ti,ab
8 (Unexpected ADJ3 (effect$ or event$ or interaction$ or outcome$ or reaction$ or response$)).ti,ab
9 (Uninten$ ADJ3 (effect$ or event$ or interaction$ or outcome$ or reaction$ or response$)).ti,ab
10 (Unwanted ADJ3 (effect$ or event$ or interaction$ or outcome$ or reaction$ or response$)).ti,ab
11 (Serious ADJ3 (effect$ or event$ or interaction$ or outcome$ or reaction$ or response$)).ti,ab
12 (tolerate or tolerability or tolerance or tolerant or hypersensativ$ or allerg$).ti,ab
13 (intolerate or intolerability or intolerance or intolerant).ti,ab
14 (toxic$ or toxin$ or intox$ or Poison$ or noxious or septic$ or hepatotoxic$ or phototoxic$ or nephrotoxic$ or carcinogenic$ or cardiotoxic$ or cytotoxic$ or Genotoxic$).ti,ab
15 (adulterat$ or contaminat$ or interact$ or pollut$).ti,ab
16 (Death$ or fatal$).ti,ab
17 (Overdose or Over-dose).ti,ab.
18 Aftereffect$.ti,ab
19 Reaction$.ti,ab
20 secondary respons$.ti,ab
21 chemically induced.ti,ab
22 Contraindication$.ti,ab
23 sequela$.ti,ab
24 (death ADJ3 sudden$).ti,ab
25 exp drug toxicity
26 Exp postmarketing surveillance
27 Exp Case Report$
28 (Case$ Adj3 (stud$ or report$ or histor$ or series$ or record$)).ti,ab
29 1 or 2 AND 3 or 4 or 5 or 6 or 7 or 8 or 9 or 10 or 11 or 12 or 13 or 14 or 15 or 16 or 17 or 18 or 19 or 20 or 21 or 22 or 23 or 24 or 25 or 26 or 27 or 28