The blue-violet dye Gentian Violet was used to treat skin diseases in the 19th century. It re-emerged in the 21st century as a cheap and easy-to-use alternative for thrush, but the FDA has issued warnings about its potential for toxicity based on animal studies. Read on to learn more about gentian violet’s uses, side effects, and risks.
What Is Gentian Violet?
Gentian violet, also known as crystal violet and methyl violet 10B, is a blue-violet dye. It’s derived from coal tar and is presently used to treat thrush (a fungal infection) of the mouth and skin [1, 2].
Gentian violet was first produced in the 19th century and was used for some time as an antibiotic and antifungal. It fell out of favor with doctors for a while as new antibiotics were developed, but it seems to be re-emerging today [1].
Gentian violet is primarily used against the fungus, Candida, which causes thrush. It also has antibacterial and antiviral activity. In Latin America, it’s used to sterilize blood transfusions and prevent transmission of the parasite that causes Chagas’ disease [1].
Gentian violet contains a mix of the following dyes [3]:
- Crystal violet 96%
- Methyl violet and brilliant green 4%
In the early 20th century, gentian violet was widely used for:
- Gum infections [4]
- Thrush [5]
- Skin infections, such as impetigo [6]
- Burns [7]
- Parasitic worms, such as pinworm [8]
- Fungal infections [9, 10]
Gentian Violet In the Era of Antibiotic Resistance
Once penicillin started to be mass produced in the 1940s, scientists focused on discovering new antibiotics. Gentian violet lost popularity and its use gradually decreased [1].
But we are now facing an opposite problem compared back to when antibiotics were just being discovered. The widespread use of antibiotics over the past decades has caused dangerous antibiotic resistance all over the world in the 21st century [1].
Gentian violet is being investigated again and being used as an inexpensive, easy-to-use alternative for skin infections. In fact, bacterial and fungal resistance to gentian violet is extremely low [1].
The FDA allows the sale of over-the-counter gentian violet, which is mainly used for [1]:
- Mouth and vaginal thrush
- Skin infections
- Disinfecting wounds
Its use is more restricted in the UK and Australia because of animal studies demonstrating the potential to cause cancer. The UK limits its application to unwounded skin, while Australia recommends the use of antifungals instead of gentian violet for mouth thrush in babies [11, 12].
Mechanism of Action
Gentian violet kills bacteria, possibly by:
- Blocking metabolism and key proteins and amino acids in bacteria [13, 14, 15]
- Binding and damaging bacterial DNA and preventing it from making proteins [16, 17]
Bacteria that can resist gentian violet are those with powerful antioxidant mechanisms (anaerobic) or with a cell wall that doesn’t allow the uptake of this drug (gram-negative) [13, 17].
In Candida, gentian violet prevents spores from maturing, growing, and making harmful proteins that cause the infection [18, 19].
Gentian violet kills the parasite causing Chagas’ disease, possibly by:
- Increasing free radicals that damage it [20, 21]
- Blocking protein production, energy, and calcium use in the parasite [22, 23, 24, 25]
Researchers are investigating whether gentian violet kills cancer cells by:
- Activating cancer-suppressing and decreasing cancer-promoting proteins [26, 27, 28, 29, 30]
- Activating cancer cell death pathways [27]
- Decreasing the formation of new blood vessels in tumors [31]
Gentian Violet Uses & Benefits
The FDA allows over-the-counter sale of gentian violet for the purpose of treating thrush of the skin and mouth, but alternatives are available. Talk to your doctor about whether gentian violet is appropriate for your case.
Likely Effective For
1) Fungal Infections
Thrush
Candida can cause thrush, a white mouth rash, especially in people with a weak immune system: the elderly, newborns, people using antibiotics, and those with chronic diseases [32].
Gentian violet has been used for thrush in babies for over 90 years. However, doctors now prefer to use nystatin and fluconazole, according to a survey of 312 doctors. They use gentian only in 1-4% of cases, and only when the other two drugs don’t work [33, 34, 35].
However, it is being increasingly used for thrush in people with HIV, especially in underdeveloped regions of the world where nystatin and fluconazole are not available [36, 37, 1].
In a clinical trial of 141 people with mouth thrush and HIV, gentian violet (0.5% solution 2 times/day) was as effective as the typical, more expensive antifungals (ketoconazole and nystatin) [38].
In another trial of 15 otherwise healthy people, a mild gentian violet solution (about 0.0016%) was effective against four Candida strains, didn’t stain the tongue, and didn’t cause adverse effects. This mild solution worked as well as antifungal drugs (nystatin) to reduce thrush in a trial of 182 people with HIV [39, 40].
However, both lemon juice and lemongrass infusions were more effective for thrush than 0.5% gentian violet 3x/day in a clinical trial of 83 people [41].
Gentian violet has also been traditionally used to improve thrush in the nipples of breastfeeding mothers passed on by their babies with mouth thrush [11].
Vaginal Yeast Infections
NOTE: gentian violet was available by prescription for vaginal yeast infections until the late 1980s, but it is currently only indicated for mouth and skin thrush. We recommend against using gentian violet against vaginal yeast infections. Safer and more effective alternatives are available; please consult your doctor.
Candida can also cause vaginal infections, and gentian violet was used to treat these for several decades [42].
In an old clinical trial of 191 pregnant women with a vaginal Candida infection, 0.2% gentian violet used over 4 weeks completely cured the infection in 78% of women. But this was a study from the 50s, while there are no recent clinical trials [43].
In multiple cellular studies, gentian violet killed Candida from the mouth, vagina, blood, respiratory tract, and ears [44, 45, 18, 46, 19].
Antifungal drugs (such as clotrimazole and miconazole) are now more commonly used and better researched for treating vaginal fungal infections. Gentian violet tampons are also available. But there is no gentian violet vaginal safety data and no up-to-date information about the best concentration or formulations for vaginal use.
Plus, let’s not forget that gentian violet is a dye that stains everything it comes into contact with. Keep that in mind before using it on any sensitive body parts.
Other Fungi
We recommend strongly against using gentian violet to attempt to treat these fungal infections. Safer and more effective alternatives are available. If you have a fungal infection, call your doctor and follow their directions.
Gentian violet has long been reported to kill fungi that may cause the following problems in humans:
- Skin infections known as Gilchrist’s disease (Blastomyces) [10]
- Skin and nail infections (Fusarium oxysporum and F. moniliforme) [47]
- Ear infections (Aspergillus niger) [48]
No clinical trials have been done, so the effects of gentian violet against these fungal infections in humans are still unknown.
One review reported the use of 1-2% gentian violet for nail fungus (onychomycosis) with good results after one month, but the data comes from an unpublished study [1].
Possibly Effective For
2) Bacterial Skin Infections
In a clinical trial on 21 people with atopic eczema and a skin infection (Staphylococcus aureus), 0.3% gentian violet for 4 days reduced both the severity of the eczema and the infection. It worked better than a tar solution or glucocorticosteroids, which only reduced eczema [49].
In five clinical trials on 91 people with skin wounds infected by methicillin-resistant Staphylococcus aureus strains (MRSA), 0.5% gentian violet killed the bacteria without causing adverse effects. Gentian violet (1% 1 time a week) also improved MRSA ear infections in a trial on 47 people [50, 51, 52, 53, 54, 55].
In studies on 97 people (2 clinical trials and an observational study), an antibacterial dressing with gentian violet and methylene blue reduced wound infections without adverse effects [56, 57, 58].
1% gentian violet combined with antibiotics (doxycycline) healed skin infections and reduced eczema in one man, suggesting its use as an alternative to steroids [59].
0.5% gentian violet was very effective against some bacteria that cause skin infections (Streptococcus and Staphylococcus), and moderately effective against others (Proteus and Pseudomonas types) in one cellular study [60].
3) Other Skin Conditions
Wounds
In a clinical trial on 200 people with burn wounds, 0.5% gentian violet caused some tissue scarring but helped the wounds heal without infection in 6-8 weeks. It was suggested as a cheaper alternative to conventional dressings [61].
In an observational study on 70 elderly people with wounds and dead skin cells, 1% gentian violet healed 103 out of 111 wounds completely [62].
Gentian violet was as efficient as a traditional moist dressing for healing wounds caused by radiotherapy in a clinical trial on 39 people but less efficient in another trial on 30 people [63, 64].
Hereditary Skin Conditions
In two children with a disorder characterized by fragile skin with blisters (epidermolysis bullosa), a mixture of gentian violet and methyl violet for 4 weeks reduced the ulcer size [65].
Gentian violet improved the condition of 2 children with a disorder that causes abnormal skin and nail thickening (pachyonychia congenita) [66].
Immune Skin Reactions
In a clinical trial on 18 healthy people, 0.5% gentian violet reduced the dermatitis symptoms caused by a skin irritant (sodium lauryl sulfate) [67].
A person with generalized itching and a rash (erythema multiforme) was cured in 3 days by applying gentian violet [68].
Gentian violet combined with other remedies improved skin symptoms in another person with damage from a rare immune condition (hypereosinophilic syndrome) [69].
4) Umbilical Cord Infections
In two observational studies on over 13 thousand low-income women who recently gave birth, umbilical cord care with gentian violet was clearly associated with reduced infection and death rates in the babies. Gentian violet has the potential to be used in underdeveloped regions [70, 71].
In a clinical trial on 766 newborn babies, the application of triple dye (gentian violet, brilliant green, and proflavine hemisulfate) 2x/day was more effective at preventing infections than simply keeping the umbilical cord clean and dry. However, triple dye with alcohol was not any better than alcohol alone in a clinical trial on 599 babies [72, 73].
Insufficient Evidence For
The following purported benefits are only supported by limited, low-quality clinical studies. There is insufficient evidence to support the use of gentian violet for any of the below-listed uses. Remember to speak with a doctor before using gentian violet, and never use it in place of something your doctor recommends or prescribes.
5) Hospital-Acquired Infections
Washing solutions with gentian violet and antibiotics healed four people with antibiotic-resistant MRSA infections and two others with hard-to-treat bacterial infections, all of which were acquired in the hospital [74, 75, 76, 77].
Coating medical devices such as catheters and tubes with a mixture of gentian violet and an antiseptic (gendine) can stop the spreading of infections through medical equipment. This combination kills infectious bacteria and yeast (Candida varieties) [78, 79, 80, 81].
6) Antiviral Activity
2% gentian violet completely resolved a tongue disease (oral hairy leukoplakia) caused by the Epstein-Barr virus in a person with HIV [82, 83].
Gentian violet had strong activity against some animal viruses deadly to humans (Hendra and Nipah) in cellular studies [84, 85, 86].
A cloth dyed with gentian violet killed the flu virus in a cell study. Cheap gentian violet-dyed face masks that protect from flu outbreaks may be developed with more studies [87].
Gentian violet certainly has antiviral potential but requires more investigation. Do not attempt to use gentian violet in this way without a doctor’s recommendation and supervision.
7) Antiparasitic Activity
Gentian violet has traditionally been used to kill the following parasitic worms
However, these parasites are nowadays killed with more effective anti-parasite drugs (such as mebendazole and albendazole) [92].
Laboratory Use
8) Blood Transfusions
Chagas’ disease is a potentially deadly tropical disease caused by a parasite that can be transmitted through blood transfusions [93].
Gentian violet kills this parasite and can be used to sterilize infected blood. The process is routinely performed in labs and has prevented thousands of people from developing Chagas’ disease without causing adverse effects [94, 95, 96, 97].
9) As a Dye
Due to its staining capacity, gentian violet can also be used [1, 3, 98]:
- As a stain to view cells and tissues in labs
- In forensics, gentian violet was used to develop latent fingerprints in surfaces
- To mark specific tissues during surgery
- To classify bacteria to those that can be stained (Gram-positive) and those that can’t (Gram-negative)
- As a dye for wood, silk, food, inks, and cosmetics
Cancer Research
1% gentian violet helped control skin cancer progression in an elderly person with poor general health status. Similarly, gentian violet resolved a cancerous skin lesion in another elderly person whose health was too fragile for normal chemotherapy [99, 100].
However, no clinical trials have confirmed the use of gentian violet for cancer.
In cell studies, gentian violet reduced the growth of and killed the following cancer types:
- Lung [26]
- Colorectal [26, 101]
- Breast [102, 28, 103]
- T-cell lymphoma [27]
- Cancer caused by asbestos (in the outer lining of organs) [29]
Gentian violet was 50 times stronger than the anticancer drug gemcitabine at preventing the growth of breast cancer in one cell study [102].
The effect of gentian violet against these cancer types in humans remains unknown.
Side Effects And Safety
Gentian violet is very messy; it stains the skin, teeth, and clothes, and almost anything else it comes into contact with. If applied on open wounds, it can temporarily tattoo the skin [11].
In addition, gentian violet can cause the following side effects when used for thrush:
- Irritation or damage to the mouth and cheek lining [104, 105, 38, 106, 107]
- Cracked lips and dry mouth [41]
- Breastfeeding difficulties [108]
- Inflammation of the larynx [109]
Frequent 2% gentian violet use on the mouth in a baby (10 – 12x/day) over 4 days caused swollen tongue, mouth injury, irritability, lack of appetite, and a hoarse cough [110].
Gentian violet use on their legs caused stinging after a few days in 2 children [65].
A high dose of gentian violet (3%) irritated the back of one person after 14 hours [111].
Although rarely, the repeated use of gentian violet can cause allergic skin reactions [112].
Workers exposed to high amounts of gentian violet (such as dye manufacturers, pulp workers, and fruit packers) reported nose bleeding [113].
Gentian violet is toxic to the eyes. It caused conjunctivitis, eye irritation, and pain in three cases [114, 115, 116].
If gentian violet is accidentally injected into the bladder during an attempt to treat vaginal thrush, it can cause severe inflammation [117, 118].
Toxicity
Gentian violet toxicity in humans is limited to case reports and only mild adverse effects have been observed in clinical trials [1].
In two long-term oral toxicity studies in mice and rats, gentian violet intake increased death rate and the incidence of several cancer types. However, gentian violet is not taken orally and no cases of cancer have been linked to applying gentian violet on the skin in over a century of use [119, 120].
In multiple studies in cells, gentian violet caused DNA mutations and abnormal cell division, which may account for the cancer effects in mice and rats. But it also has anticancer activity, which is not that unusual for chemotherapy drugs. Many drugs that can kill cancer cells can also cause cancerous changes in healthy cells. In the case of gentian violet, further investigation is needed [121, 122, 123, 124].
Limitations and Caveats
Most human studies investigating the health benefits of gentian violet are clinical trials with few people or case studies. Additionally, a lot of studies were carried out over 50 years ago. They are difficult to evaluate because the composition of the gentian violet preparations used varied and authors often didn’t clearly describe it [1].
Similarly, the activity of gentian violet against harmful microorganisms and cancer cells has mostly been investigated in cell studies.
Gentian Violet Supplementation
Dosage
Gentian violet can be directly applied to the affected area of the skin or mouth with a cotton swab or a dressing. Please discuss the appropriate use of gentian violet and any alternatives with your doctor before proceeding.
- 0.5% – 1% gentian violet 1 – 2x/day is the dose commonly used for mouth thrush in babies and adults with a weakened immune system [35, 38].
- In breastfeeding women with thrush on the nipples, a 0.5% gentian violet solution has been safely used for no longer than 7 days [125].
- For other skin conditions, 0.1% – 2% gentian violet has been applied 1x to 2x/day [54, 51, 59, 61, 62, 83].
- For umbilical cord care, a triple dye containing 0.25% gentian violet has been applied 2x/day [72, 73]
Hospital-acquired infections improve after daily irrigation with 0.1 – 0.2% gentian violet, normally in combination with antibiotics. This should not be attempted without the supervision of a doctor [76, 77, 74].
Drug Interactions
No interactions of gentian violet with other drugs have been described. Gentian violet didn’t interact with an antifungal drug (fluconazole) in one cellular study [46].
Takeaway
Gentian violet is a blue-violet dye derived from coal tar which, for much of the early 20th century, was used as a common treatment for thrush and some other skin, mouth, and vaginal infections. Today, there are better alternatives available, but gentian violet may once again see some use where conventional therapies are unavailable or inappropriate. For example, it can help kill bacteria that have developed antibiotic resistance.
Gentian violet’s most significant potential uses are tied to its antimicrobial activity. It kills many fungi, bacteria, viruses, and even parasitic worms on contact. It can even be used to prevent Chagas’ disease transmission during a blood transfusion.
Gentian violet may cause staining, irritation, and inflammation, especially after repeated use. Animal research also suggests some carcinogenic potential, though no human cancer cases have yet been attributed to the use of gentian violet.
