Considering the number of negative cases in literatures, bee propolis can be claimed as a very safe supplement. The only side effect which taken seriously by most people is allergic reaction. A journal from Italy, titled Surveillance ofsuspected adversereactions to natural health products: the case of propolis gives us clear example about how bad this side effect can be. It is reported that during 5 years period (2002 – 2007), there are:
- 16 reports about allergic reactions in a form of dermatitis and/or respiratory problem,
- 2 reports regarding digestive tract.
From those total 18 cases, there are 6 patients who go to emergency departments, and 2 patients suffer life-threatening side effects.
The Other Side EffectsRegardless of its allergic reaction, systemic toxicity of bee propolis is not something that often reported, and hence, may be underestimated. When I dig deeper about this topic, there are at least three possible side effects that might be caused by propolis consumption:
- Acute renal failure
- Mutagenic and Genotoxic
- Cytotoxic effect
Renal FailureAs far my research goes, there are at least two documented cases of acute renal failure that is suspected as a result of propolis side effect:
- Reported by
Li from Hospital of Chang Gung Memorial in Taipei  .
The first renal failure incident was happening on a 59 years old man who suffers for bile duct cancer. During 2 weeks period, he consumed Brazilian propolis to help his cancer treatment. Starting that time, his renal function began to deteriorate.
After stopping the consumption, his renal function was improving. However, he then decided to consume it again for the second time, and his renal function got worsened again. After he completely stopped the consumption, his renal function back to normal.
- Reported by
Canadian Adverse Reaction Newsletter. 
The second case of suspected side effect was happening on a 3 years old boy. He was suffering for gluten enteropathy – a disorder in nutrients absorption which caused by gluten allergy. He consumed propolis to prevent infection possibility that might be caused by his disease. The boy himself was diagnosed for suffering acute renal failure after he had consumed bee propolis 2 – 3 times each week for 4 months periods. The renal failure symptom was shown by his excessive creatinine level. Right after he stopped the consumption, his creatinine level back to normal, and with restricted diet, his gluten enteropathy disease was getting better.
Mutagenic and Genotoxic Effects
Speaking about the second possible side effects, there are mutagenic and genotoxic effects. These two possibilities were shown by in-vitro study conducted by Rodrigues C.R.
These harmful effects are identified by investigating the vegetation source of Brazilian bee propolis which is known as Baccharis dracunculifolia.Mutagenic effect can be defined as alteration of genetic material (usually refer to DNA). This kind of effect is considered to be accountable for cancer disease. Mutagenic effect refers to genetic material alteration, while genotoxic specifically refer to chromosomal damage which may result in mutagenicity.
The study shows that the extract of Baccharis dracunculifolia is capable to cause DNA deterioration in the blood tissues, liver tissues and micronucleus of bone marrow in mice. If the main vegetation source has such a harmful effects, it is assumed that the derivative product (Brazilian bee propolis) can also produce the same negative effects.
Rodrigues’ work seems to be followed up recently by study conducted by Montoro. Rather than using mice as an experiment subject, Montoro used human lymphocytes cells and tested the possible propolis side effect effects by using high concentrated ethanolic extract. In conclusion, the study assumes that cytotoxicity and genotoxicity on human peripheral lymphocytes might be happen as possible propolis side effects . And in a separate study, other researchers have the same conclusion for this genotoxic effect.Cytotoxic means a capability of being a toxic to cell. This effect may have variety results. It can cause cell lysis/apoptosis or even mutagenicity.
However, please note that these genotoxic effect is present in abnormal excessive consumption.
- LiYJ.Lin JL.CWYang.CCYuAcute renal failure caused by a Brazilian bee propolis. Kidney Disease. 2005 Dec;46(6):e125-9
- Canadian Adverse Reaction Newsletter Volume 19 - Issue 1 - January 2009; about suspected propolis side effects
- RodriguezCR, Dsia5JH, JG Sem3d0. Mutagenic effect and genotoxic effect produced by Baccharis dracunculifolia (D.C.).J Ethanopharmacol. 2009 Jul 15;124(2):321-4. Epub 2009 May
- AMont0row. JMSoriano. JFBarquinero. Invitro experiments regarding cytotoxicity and genotoxicity as possible propolis side effects on lymphocytes cell of mankind. Food Chemical Toxicology. 2011 Oct 25.
- Ozkul Y, Eroglu HE, Ok E. Genotoxic potential of Turkish propolis in peripheral blood lymphocytes. Pharmazie. 2006 Jul;61(7):638-40.