How Long Does It Take For A Dandruff Shampoo To Work?

The short answer to How Long Does It Take For A Dandruff Shampoo To Work is days to weeks. But there is a lot to learn about different products on the market and about the active and inactive ingredients they contain.

 Let’s start by defining what makes a “medicated shampoo.”

What Is A Medicated Shampoo?

In the 1980s, the FDA wanted to weed out the snake oils of the shampoo world. So, all products that were purported to help dandruff, seborrheic dermatitis, and psoriasis were asked to submit data from clinical trials supporting the claims they were making.

When it came to treating seborrheic dermatitis, the following ingredients at certain percentages made the cut: 

• pyrithione zinc
• selenium sulfide
• coal tar
• salicylic acid.

Later, the active ingredient ketoconazole was added to the list. When I say “made the cut,” it means these ingredients (formally called “Active Ingredients”) had to prove they were both safe and effective.

These 5 ingredients, when made at the required percentage, with the appropriate labeling, and using factories that follow stringent manufacturing processes, are called OTC (Over-the-counter) medicated shampoos.

Medicated Shampoo Labels Are Important

When purchasing an OTC medicated shampoo for seborrheic dermatitis, you will notice a familiar label on the back of the bottle or packaging called a “Drug Facts” label. This helps you easily identify which Active Ingredient is featured in each medicated shampoo. 

Some medicated shampoo brands make different product lines with different active ingredients for different skin conditions. Read that label!

A few lines down from the top of that label, you will find the subheading “Directions” and then the following lines that say something like, “For best results use at least twice a week or as directed by a doctor.”

You may wonder why there are even different products on the market if they all say the same thing.  When claims for these active ingredients were evaluated in the 1980s, the experts weighed in. They decided that if used with a specific frequency (two times per week), after a couple of weeks, people would indeed see less flaking, scaling, and irritation associated with seborrheic dermatitis. So yes, all OTC medicated shampoos do work to fight flakes.

What distinguishes one medicated shampoo from another?

People react differently to different active ingredients. For example, one person may not like what their skin feels like with salicylic acid, while another person finds the smell of coal tar or selenium sulfide offensive.

Some may find pyrithione zinc to be too gentle or ketoconazole to be too drying. Each brand of shampoo uses different active ingredients at different percentages to deliver the active ingredient to your scalp and skin in order to accomplish the task of improving the symptoms of seborrheic dermatitis and dandruff. 

It is similar to Tylenol and Ibuprofen; they both reduce fever and pain, but people have a preference on which one works best for them.

Importance of Inactive Ingredients In Products

A big distinguishing factor that we have yet to discuss is the inactive ingredient and the importance of what a medicated shampoo does not contain. Inactive ingredients are the crucial vehicles that make the product foam and help to wash away accumulated oils on the scalp and body.

Many companies have added “natural” inactive ingredients that help to soothe or soften the skin or moisturize the hair. Most products have scent or color, as many people find odors and colors a pleasing experience.

However, many adults with seborrheic dermatitis will describe themselves as having sensitive skin. Children have sensitive skin. These groups of people will benefit from avoiding products that contain common skin irritants like fragrances and artificial dyes. These folks should look for a medicated shampoo that is fragrance-free, dye-free, paraben-free, and sulfate-free.

Cradle Cap And Seborrheic Dermatitis

If you are an adult reading this article, you may have been surprised to see children mentioned in the paragraph above. Infants get “cradle cap.” Cradle cap is the scaling and flaking that occurs on the scalp and eyebrows. We see it in kids as young as 3-4 weeks old. Cradle cap is an infant version of seborrheic dermatitis. About 33% of kids persist with cradle cap through the age of 5 years old. 70 percent of pediatricians suggest using an OTC Medicated Shampoo to get rid of cradle cap. Until a couple of years ago, there was no product created specifically with children in mind.

How Does Anti Dandruff Shampoo Work?

Anti dandruff shampoo contains active ingredients that help reduce flaking and scaling. These active ingredients help control and maintain the presence of Malassezia fungus on the skin and scalp, which is a primary factor that causes irritation, scaling, and flaking associated with dandruff, seborrheic dermatitis, and cradle cap.

When Malassezia fungus on the skin combines with sebum, it creates a byproduct known as oleic acid. It irritates the skin and causes flakes and redness. The active ingredients in dandruff shampoo reduce the amount of oleic acid produced by the fungus.

How To Use Dandruff Shampoo?

It is important to use anti dandruff shampoo properly to get optimal results. The most important thing is to read the how-to-use label mentioned on the product and use it accordingly or as advised by the dermatologist. 

• Dandruff shampoo should be used in small amounts at least twice a week.
• Massage the shampoo on the scalp, focusing more on the scalp rather than the hair. 
• Massage the shampoo in slow, circular motions. 
• Leave it on the scalp for a minute or two.
• Then, rinse the scalp with lukewarm or cool water.
• Make sure there is no residue left behind.

Which Ingredients To Look For In Dandruff Shampoo?

Some important active ingredients that help reduce scaling and flaking associated with dandruff, seborrheic dermatitis, and cradle cap are

• Ketoconazole
• selenium sulfide
• Zinc pyrithione
• Salicylic Acid
• Coal Tar

Each ingredient works differently. Some help fight and reduce Malassezia yeast on the scalp, while others may help reduce skin cell turnover. To ensure which will be the best ingredients or dandruff shampoo for your scalp, it is best to consult your primary care physician or a dermatologist.

How long does it take to get rid of seborrheic dermatitis?

Some people may see results in as few as one or two washes.  However, most will see significant improvement after 1 to 2 weeks of use. If there is much scale build up as you find in cradle cap you may need to use a medicated shampoo for seborrheic dermatitis daily for 3 to 7 days (Many OTC shampoos can be used daily as tolerated). People with thick scale build-up should consider leaving the shampoo on for 1-2 minutes before rinsing. People in this latter category should start to see results in 2-3 weeks. Once the scaling and flaking are under control, we suggest tapering use to 2-3 times per week.

References:

1. 358.710 Active ingredients for the control of dandruff, seborrheic dermatitis, or psoriasis. PART 358 — MISCELLANEOUS EXTERNAL DRUG PRODUCTS FOR OVER-THE-COUNTER HUMAN USE. Code of Federal Regulations. Title 21, Volume 5. Revised as of April 1, 2019. CITE: 21CFR358.710 https://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/CFRSearch.cfm?fr=358.710 . Accessed 9 April 2020.

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Dr. Eddie Valenzuela

Dr. Eddie Valenzuela is an award winning pediatrician and the founder and CEO of Pediatric Solutions, LLC.

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