Selsun Blue can be used as a body wash to treat common skin fungal infections, particularly tinea versicolor (also called pityriasis versicolor), the condition that causes light or dark patches on the chest, back, and shoulders. The active ingredient, selenium sulfide, works by breaking down the bonds between dead skin cells and promoting shedding of those cells along with the fungus living on them. It also has direct antifungal activity against Malassezia, the yeast responsible for tinea versicolor.
Step-by-Step Application
The process is straightforward, but the key detail most people miss is the contact time. You need to leave the product on your skin for a full 10 minutes before rinsing. Simply lathering and rinsing off in the shower like a normal body wash won’t give it enough time to work.
Here’s how to do it:
- Apply to affected areas. Spread the shampoo directly onto the patches of discolored or flaky skin. Avoid your face and genitals.
- Lather with a small amount of water. You don’t need much. Just enough to work the product into a thin lather across the affected skin.
- Wait 10 minutes. Leave the lather on your skin. Set a timer. This is the step that makes the treatment effective.
- Rinse thoroughly. Use warm water and make sure all residue is completely removed.
Many people find it easiest to apply the product before getting into the shower, let it sit while they do other things, then rinse at the end. If your affected area is on your back and hard to reach, applying it before a bath or asking someone to help can make coverage more even.
How Often to Apply
For an active tinea versicolor infection, a common approach is applying the shampoo once daily for seven days, or once weekly for several weeks. In a clinical trial comparing selenium sulfide to another antifungal shampoo, subjects applied the product once a week for three weeks and saw cure rates around 85 to 86%. Some dermatologists recommend daily application for a shorter burst, while others prefer the weekly schedule. Either way, expect to continue treatment for at least two to four weeks.
Once the infection clears, many people use it once or twice a month as a preventive measure, since tinea versicolor has a strong tendency to recur, especially in warm, humid weather.
OTC vs. Prescription Strength
Selsun Blue sold over the counter contains 1% selenium sulfide. Prescription-strength formulations contain 2.5% selenium sulfide and are sometimes recommended for stubborn or widespread infections. The 1% version works for many mild to moderate cases, but if you’re not seeing improvement after a few weeks, a stronger concentration may be needed.
When shopping, check the active ingredient label. Some Selsun Blue varieties use pyrithione zinc instead of selenium sulfide. You specifically want a bottle listing selenium sulfide as the active ingredient.
How It Compares to Other Antifungals
Selenium sulfide performs comparably to ketoconazole, the other widely used antifungal shampoo for tinea versicolor. In a randomized controlled trial, selenium sulfide cleared the fungus in 86% of participants by day 14, while ketoconazole cleared it in 94%. That difference was not statistically significant, meaning both treatments are considered similarly effective. Notably, selenium sulfide caused fewer side effects: only 8% of participants reported irritation at the one-week mark, compared to 22% in the ketoconazole group.
Where Not to Use It
Do not apply selenium sulfide to your face, genitals, or broken or inflamed skin. The product is designed for intact skin on the body and scalp. If you have fungal patches on your face, a different antifungal cream is a better choice. Also avoid getting it in your eyes, as it can cause significant irritation.
If you have cuts, sunburned skin, or areas of eczema in the treatment zone, wait until those heal before applying. Selenium sulfide on damaged skin can cause stinging and worsen irritation.
What to Expect During Treatment
The fungus itself may clear within one to two weeks, but the discolored patches on your skin often linger for weeks or even months afterward. This is normal. The yeast disrupts your skin’s pigmentation, and that color difference takes time to even out as your skin naturally regenerates. Sun exposure can make the contrast more obvious, so the patches tend to look worse in summer even after the infection is gone.
Some dryness or mild irritation is possible during treatment. If the product makes your skin feel tight or flaky, you can apply a fragrance-free moisturizer after rinsing, once the skin is completely dry. Significant burning, redness, or a rash that spreads means you should stop using it.
If you’ve been using Selsun Blue consistently for three to four weeks with no improvement in the scaling or itching, the issue may not be tinea versicolor. Other conditions like eczema, vitiligo, or a different type of fungal infection can look similar but won’t respond to selenium sulfide.