The blue-violet dye Gentian Violet was used for skin diseases in the 19th century. Today it’s re-emerging as a cheap and easy-to-use alternative for thrush, fighting bacterial skin infections, parasites, and fungal infections. Read on to learn more about gentian violet, its uses, benefits, and side effects.

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 traditionally used as a remedy for skin conditions [1, 2].

Gentian violet was first produced in the 19th century and has been used ever since as an antibiotic for various diseases. It fell out of favor with doctors for a while as new antibiotics were developed. But now its use is re-emerging as new benefits are being discovered [1].

Gentian violet can combat viral, bacterial, parasitic, and fungal infections. It even has some cancer-fighting activity. In labs, it’s used to sterilize blood infected with 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 caused dangerous antibiotic resistance all over the world in the 21st century. Gentian violet is being investigated again and being used as an inexpensive, easy-to-use alternative with few side effects for skin infections. In fact, 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
  • Wounds
  • Blood transfusions: preventing Chagas’ disease spreading through infected blood by adding gentian violet

Its use is more restricted in the UK and Australia due to its cancer-causing potential. 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 strong 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]

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

1) Fights Fungal Infections


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].

But 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 equally effective as the typical, more expensive antifungals (ketoconazole and nystatin) [38].

In another trial of 15 healthy people, a mild gentian violet solution (about 0.0016%) was effective against four Candida strains, didn’t stain the tongue, or 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

Candida can also cause vaginal infections [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

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.

Analyses reported the use of 1-2% gentian violet for nail fungus with good results after one month [1].

2) Improves 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) Improves Other Skin Conditions


In a clinical trial on 200 people with burn wounds, 0.5% gentian violet caused some tissue scarring but helped heal the wounds 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 very 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) May Prevent 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].

5) May Reduce 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) Has Anticancer Activity

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 [82, 83].

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, 84]
  • Breast [85, 28, 86]
  • 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 [85].

The effect of gentian violet against these cancer types in humans remains unknown.

7) Fights Viruses

2% gentian violet completely resolved a tongue disease (oral hairy leukoplakia) caused by the Epstein-Barr virus in a person with HIV [87, 88].

Gentian violet had strong activity against some animal viruses deadly to humans (Hendra and Nipah) in cellular studies [89, 90, 91].

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 [92].

Gentian violet certainly has antiviral potential but requires more investigation.

8) Kills Parasitic Worms

Gentian violet has traditionally been used to kill the following parasitic worms

  • Pinworms [93, 94, 8]
  • Threadworms [95]
  • Small intestine roundworms [96]

However, these parasites are nowadays killed with more effective anti-parasite drugs (such as mebendazole and albendazole) [97].

9) Used in Blood Transfusions

Chagas’ disease is a potentially deadly tropical disease caused by a parasite that can be transmitted through blood transfusions [98].

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 [99, 100, 101, 102].

10) Other Uses (Scientific)

Due to its staining capacity, gentian violet can also be used [1, 3, 103]:

  • 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

Side Effects

Gentian violet is very messy, stains the skin, teeth, and clothes, and anything 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, it can cause severe inflammation in both babies and adults [117, 118].


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].


Gentian violet can be directly applied to the affected area with a cotton swab or a dressing.

  • 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 can be used for no longer than 7 days [125].
  • For other skin conditions, 0.1% – 2% gentian violet can be applied 1x to 2x/day [54, 51, 59, 61, 62, 88].
  • For umbilical cord care, a triple dye containing 0.25% gentian violet is applied 2x/day [72, 73]

Hospital-acquired infections improve with the daily irrigation with 0.1 – 0.2% gentian violet, normally in combination with antibiotics [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].

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.

User Experiences

Most users employed gentian violet for mouth thrush in babies or the nipple thrush in breastfeeding women. They generally reported good outcomes within 1 – 3 days, even those who had previously tried nystatin without results. Only a few users complained that it didn’t work for them.

Those using gentian violet for vaginal candidiasis, ear infections (either for themselves or for their pets), and wounds were equally satisfied with its effects.

A lot of people using gentian violet for less-researched conditions (fungus nail, ringworm) complained that it didn’t work.

Most reviews, even those who reported satisfactory results, pointed out that gentian violet will stain the skin and clothes. This was the main reason for disappointment. The users normally employed hand sanitizer or alcohol to wash it off, when possible.

Less frequent complaints included skin irritation and its bad taste when applied in the mouth.

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About the Author

Carlos Tello, PhD (Molecular Biology)

PhD (Molecular Biology)

Carlos received his PhD and MS from the Universidad de Sevilla.

Carlos spent 9 years in the laboratory investigating mineral transport in plants. He then started working as a freelancer, mainly in science writing, editing, and consulting. Carlos is passionate about learning the mechanisms behind biological processes and communicating science to both academic and non-academic audiences. He strongly believes that scientific literacy is crucial to maintain a healthy lifestyle and avoid falling for scams.

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