Monday is a hair care brand with beautifully designed products. The brand sells shampoo and conditioner, has won several beauty awards including Glamour’s award for “Best Drugstore Shampoo and Conditioner for Frizz.”
But does Monday use research-backed ingredients for improving hair quality? Does it contain any unhealthy ingredients? Is Monday Conditioner a healthy option? And what was our Product Tester's honest experience trying Monday Shampoo?
In this article we’ll answer all of these questions and more, as we analyze the ingredients in Monday shampoo and conditioner to give our take on whether or not the products are likely to support hair quality and appearance, and whether or not they're healthy.
We'll also share our Product Tester's honest experience after trying Monday Shampoo for a month, and compare Monday Shampoo to other popular shampoo brands like Maui Shampoo to pick our winners (and losers).
Key takeaways:
- Contains research-backed active ingredients
- Contains inactive ingredients we consider unhealthy
- We do not currently recommend Monday Shampoo
Shampoo Ingredient Analysis
The ingredients in Monday Smooth Shampoo are shown below:
This formulation includes active ingredients shown in clinical studies to improve hair quality.
Hydrolyzed wheat protein was shown in a 2018 medical review to be non-toxic and to effectively condition hair.
Dimethiconol is a compound derived from silicone that's clinically shown to protect hair color, and to protect hair from UV damage, as we documented in our article on is BioSilk good for your hair.
Glycerin can improve skin barrier function and reduce dandruff according to a 2014 clinical trial.
There are also a number of ingredients we recommend avoiding.
Fragrance is included, and a medical review on fragranced consumer products published in the Air Quality, Atmosphere & Health journal concluded the following:
“Results of this study provide compelling evidence that everyday fragranced products can impose serious risks to human health, environmental quality, businesses, and society.”
Sodium benzoate, phenoxyethanol and ethylhexylglycerin are synthetic preservatives, and at least one of them was shown to be toxic to human cells in a clinical trial.
Cocamidopropyl betaine is a synthetic detergent ingredient that won an award called Allergen of the Year in 2004 according to a medical review on the ingredient, due to how frequently it caused skin sensitivity reactions.
We consider Monday Smooth Shampoo likely to support optimal hair quality given its active ingredients.
However, we don't currently recommend this shampoo overall due to our concerns about the health effects of some of its inactive ingredients discussed above.
We Tested Monday Shampoo
One of our product testers named Hannah Westerman tried Monday Shampoo for a month. Here's her experience:
The experience was great. No issues opening or using. The packaging is beautiful.
It smells SO good! I love the way it leaves my hair smelling too.
This shampoo really made my hair softer. It has a conditioning effect, and paired with my conditioner, left my hair feeling soft and smooth!
I did not experience any side effects from Monday Shampoo.
Overall, I would rate this product 10/10, and I plan on purchasing it again.
Conditioner Ingredient Analysis
The ingredients in Monday Smooth Conditioner are shown below:
Like the shampoo, this formulation contains some research-backed active ingredients.
Coconut oil is one of the best botanical ingredients for hair, as it was shown in a medical review published in the Journal of Cosmetic Science to prevent hair damage and reduce hair protein loss “remarkably” in both damaged and undamaged hair.
Shea butter is a moisturizing ingredient that has anti-aging effects, according to a medical review published in the Molecules journal.
Fragrance, ethylhexylglycerin and phenoxyethanol are all inactive ingredients we recommend avoiding when used in combination, for reasons described in the previous Ingredient Analysis section of this article.
It's also notable that ethylhexylglycerin and phenoxyethanol are clinically shown to be more toxic in combination than when used separately, as we documented in our is Cantu bad for your hair article.
Overall, we consider Monday Smooth Conditioner likely to improve hair quality due to its active ingredients.
We do not currently recommend this conditioner because of the inactive ingredients discussed above.
Monday Shampoo vs. Popular Shampoo Brands
Here's how Monday Shampoo compares to other popular shampoo brands in terms of potential effectiveness and healthiness, in our opinion:
Maui
Contains a synthetic preservative which releases formaldehyde, and which is clinically shown to have potentially cancer-causing effects.
Winner: Monday Shampoo
Kristin Ess
Contains fragrance and at least one version contains synthetic dye, as we documented in our Kristin Ess shampoo review article.
Monday Shampoo is synthetic-dye-free, so it gets the (slight) edge from a healthiness perspective.
Winner: Monday Shampoo
Raw Sugar Shampoo
Also contains fragrance and synthetic preservatives, but contains fewer synthetic preservatives than Monday Shampoo.
Winner: Raw Sugar Shampoo
Our Clean Hair Care Picks
Acure Vivacious Volume Shampoo is our top shampoo pick.
It contains argan oil which is clinically shown to help protect hair from damage.
Ritual HyaCera is our top hair growth supplement.
This supplement contains wheat oil extract, and a 2024 clinical trial reported that a wheat lipid complex had "a reducing effect on hair shedding and a stimulating effect on hair reappearance and growth."
Both of the products recommended in this section are free of ingredients we consider to be unhealthy.
Monday Shampoo Pros and Cons
Pros:
- Great branding
- Affordable
- Contains research-backed active ingredients
- Both products should support hair quality
- Both products should support hair appearance
- Brand has slightly improved formulations since our initial review
Cons:
- Contains fragrance
- Contains phenoxyethanol and ethylhexylglycerin
- Contains other synthetic preservatives
- Some online reviewers report hair loss
