Gentian violet has been used since the late 19th century to treat thrush infections, but its use has currently been largely discouraged by medical authorities in favor of safer alternatives.

However, gentian violet has recently become associated with serious health risks. Modern research has associated gentian violet with potential higher risks of:

  • cancers
  • DNA changes
  • toxicity, especially in mucous membranes
  • potential allergies

Gentian violet is a synthetic antifungal and antiseptic dye that has long been known as an inexpensive treatment of thrush and other fungal skin yeast infections, such as ringworm and athlete’s foot. It has also been used as an antibacterial to prevent infection of minor cuts.

The name “gentian violet” refers to the chemical’s resemblance to the intense purple-blue color of gentian wildflowers. It has been around since the 1860s. Though named after a flower, it is in fact produced industrially.

Traditionally used to treat fungal infections, such as oral thrush infections in babies and in people with HIV, gentian violet also has mild antibacterial and antiviral properties.

Gentian violet is still used to treat thrush, but its therapeutic role is controversial.

People and clinicians continue to use it because it is known to be very effective against thrush, and it is inexpensive. Cost can be a critical factor in communities and health facilities around the world where finances are limited.

Gentian violet is also an option to treat thrush in people where Candida albicans, the fungus that causes thrush, develops resistance to antifungal medications.

This resistance occurs when the fungi become able to defeat the drugs designed to stop them, and the treatment fails.

Antifungal resistance can be a serious complication for people if fungal infections are left untreated. Some fungi have the ability to spread systemically and affect vital body components such as blood, heart, brain, and eyes.

Research has shown that Candida albicans, which causes thrush, is one fungus that can do this.

Gentian violet was a popular thrush treatment until the second half of the 20th century when the first antifungal nystatin was produced in 1949, followed by the azole antifungals in 1969.

The use of gentian violet to treat thrush declined in the face of these new antifungal medications, which proved very effective in treating thrush.

Now that antifungal resistance has risen in tandem with antibiotic resistance throughout the world, gentian violet is making something of a comeback. Some researchers say gentian violet provides a widely available and effective treatment for thrush infections.

The majority of medical practitioners and regulatory agencies worldwide want to put the brakes on gentian violet’s comeback, especially for use in children and babies.

In light of recent research in animals pointing to potential serious health risks involving the use of gentian violet, many authorities advise caution.

In 2013, the World Health Organization (WHO) declared gentian violet genotoxic (potentially damaging to DNA) and carcinogenic. It declined to issue an ADI (advisable daily intake) because of these safety issues.

Gentian violet medical use has been banned in some countries and curtailed in others. Read on to see some examples.

  • United States
  • Canada. In 2019, all nonprescription products containing gentian violet for human use and veterinary products were removed from sale in Canada. Health Canada cancelled all licenses for these products after its safety review showed gentian violet could be linked to an increased risk of cancer.
  • Europe. The United Kingdom (UK) and France have also limited the use of gentian violet. The UK allows its use only on unwounded skin. France has banned the use of gentian violet cosmetic products.
  • Australia. Australia declared gentian violet (called crystal violet) a potential risk to public health in 1994. It canceled clearance certificates for products containing it for both use on human skin and veterinary use.

The Centers for Disease Control and Prevention (CDC) recommends the following topical medications for thrush, and does not mention gentian violet:

Also, the Infectious Diseases Society of America omits gentian violet from the 2016 update of its guidelines for management of candida infections.

Research about the safety of gentian violet is mixed.

As mentioned above, gentian violet has been identified as a potential carcinogen, mutagen (substance causing DNA mutations), and toxin. Also, reports have been made about side effects in babies, including:

  • irritation of the skin and mouth
  • mouth ulcers
  • inflammation of the esophagus and throat
  • swelling of the face

One 2020 research review and one 2017 study found gentian violet as effective as the drug nystatin in treating HIV thrush infections.

Even though these and earlier studies have shown gentian violet to be effective in treating thrush, regulatory agencies currently tend to favor the azole antifungal drugs instead as they are known to be safe, inexpensive, and widely available.

To understand why gentian violet is sometimes used to treat thrush, it’s important to know what thrush is. Candida albicans — a form of yeast that lives on your skin and in your mouth and digestive tract — is usually kept under control by friendly bacteria and microorganisms.

But when the delicate balance is upset, Candida albicans flourishes. This overgrowth is known as thrush.

Thrush typically shows up in its oral form as white patches in a baby’s mouth and on their tongue and gums. And it can make feeding time quite painful, so if your baby is extra fussy at this time, you might have a good idea of what to blame.

If you are breastfeeding or chestfeeding, symptoms of thrush are often some scaling and redness around your nipples. Or you may notice a deep, burning pain that lasts through the feeding.

Besides people who are breastfeeding and babies, people commonly affected with thrush include:

  • older people, especially those with multiple underlying conditions
  • people living with HIV, AIDS, or other immunodeficiencies
  • people receiving critical care
  • people receiving cancer treatment

In terms of drawbacks, the main one is safety, especially with babies and children.

Another drawback is that is can be messy. It’s called gentian violet dye for good reason. If you use it, watch out because it can stain your clothing permanently. While your baby won’t mind the color, you probably will. To minimize the paintwork, undress your baby before they feed and remove your own shirt.

Side effects sometimes occur when using gentian violet. Those reported include:

  • Irritation. High concentrations of gentian violet have been associated with skin irritation, especially of the lining of the eyes, gastrointestinal tract, and genital tract. Always use low-concentration doses.
  • Toxicity. Gentian violet has been linked to nausea, vomiting, diarrhea, and abdominal pain.
  • Ulcers. Gentian violet has been reported to cause oral ulcers in some people.

In general, don’t use gentian violet:

  • on open wounds, including cracked nipples
  • near the eyes

Discuss using gentian violet with your doctor before starting it for yourself or your baby.

If you’ve been using gentian violet for a week and don’t see an improvement, reach out to your healthcare professional to see whether there’s another reason for the pain you feel.

Also, if you’ve used gentian violet successfully twice and are now experiencing a third thrush infection, speak to your doctor to try to figure out why the reinfection is happening.

Finally, if this is your first yeast infection, or you’re unsure whether it’s really thrush, have your doctor assess you.

If your baby develops mouth ulcers from the treatment, stop using gentian violet and consult your pediatrician. The sores should clear up within a day. You should also notify the doctor if your baby isn’t feeding well or wetting the usual amount of diapers.

Gentian violet can be an effective treatment for thrush, but it has potential health risks and side effects. Before you use it for yourself, your children, or others, you will want to check with a medical professional for advice.

If you do decide to use it, be very careful to follow your doctor’s dosage and use instructions. Solution strength and dosage amounts are especially important when using gentian violet. Using too much or too strong of a solution can cause side effects.

Treatments for thrush other than gentian violet include the azole antifungal medications. These require a prescription. Your doctor can help you decide which treatment is best for your particular situation.