The Real Science Behind Hair Damage
Why your hair looks dull, dry, or frizzy—and what to do to heal and protect it for good.
Your hair goes through a lot more than you think. Even without the heat tools, bleach, or tight ponytails, simply living in the Philippines—where humidity, saltwater, and chlorinated pools are part of daily life—can leave your strands dry, brittle, and prone to breakage.
And while social media might promise a miracle mask or a viral serum, the truth is: lasting hair repair needs more than a one-wash wonder. To understand what your hair really needs, we asked top experts to break down the science of hair damage, the root causes, and the best scalp and hair treatments to restore your strands—based on your hair’s current condition.
Meet the Experts
- Alex Carbonell is the creative director of Studio Fix by Alex Carbonell and the creative learning director of Bench Fix.
- Rafael Fortus, MD is a hair restoration expert and medical director of Clinique de Paris.
First Things First: Hair Is Dead—But How You Treat It Matters
Let’s get a little technical for a moment. Hair is made up of three parts: the cuticle (the outer layer), the cortex (where chemical treatments take effect), and the medulla (the innermost part). It’s mostly keratin, a tough protein produced by the body—but once it leaves your scalp, hair is technically “dead.”
Still, what you eat, how you treat your scalp, and your day-to-day hair habits affect how healthy and beautiful your strands look. “Keratin production relies on protein-rich food and a stress-free lifestyle,” says Carbonell. Think of it as self-care, from root to tip.
Dr. Fortus compares hair to a flower: “It needs sunlight, water, and good soil. In hair terms, that’s proper circulation, a clean scalp, and nutrients.” Deficiencies in vitamins like biotin, vitamin D, and zinc? You’ll see the signs on your head first.
The Buzzword You Need to Understand: Hair Porosity
Hair porosity—aka how your hair absorbs and retains moisture—is having a moment on social media. But Carbonell breaks it down like this: low porosity resists moisture (usually due to product buildup), while high porosity sucks in moisture but can’t retain it (thanks to damage from heat, bleach, or treatments).
Carbonell categorizes hair into porosity types using pH levels—a scale from 1 (most acidic) to 14 (most alkaline). Ideal, balanced hair? Around a pH of 7.
Here’s how to know your hair’s porosity—and what to do:
1. Poor Porosity (pH 3)
Signs: Itchy, oily, inflamed scalp. White or silver hair left untreated.
Goal: To soothe and bring the scalp back to its healthy state.
Skip: All chemical services like coloring and hair texture treatments as they will all sting and irritate your scalp further.
Expert Recommendation: “Scalp conditions like seborrheic dermatitis, eczema, and psoriasis create an environment hostile to hair growth,” says Dr. Fortus. Because this is a medical condition, seeking medical attention should be your first course of action.
Medical treatments such as topical serums as well as a more holistic approach with plasma treatments and exosome therapies, which encourage overall hair growth, are available depending on your condition’s severity and your budget.
2. Oily or Flaky Scalp (pH 4–5)
Signs: Dandruff, excessive oil.
Goal: Detox and clear the scalp, unclogging the root of excess oil and flakes.
Expert Recommendation: Intensive scalp cleaning with exfoliating ingredients and manual exfoliation through a massage. Carbonell recommends the L’Oréal Professionnel Serioxyl Advanced Purifier bodifier shampoo followed by L’Oréal Professionnel Serioxyl Advanced denser hair density activator serum.
3. Greasy or Flat Hair (pH 6)
Signs: Missed a shampoo, limp hair.
Goal: Bring back volume and shine to limp and dull hair.
Expert Recommendation: Carbonell recommends the seven-step in-salon Milbon Plarmia Scalp Treatment and the products from the same line for its pH balancing benefits.
4. Normal Porosity (pH 7)
Signs: Untreated hair, decent density, minor exposure to stressors like sun and wind.
Goal: To protect hair from damage while adding density and shine without weighing hair down.
Expert Recommendation: For thin hair, well-executed haircuts with texture, volumizing mousse, thickening shampoo, and conditioner all work together to make hair look thicker while being lighter, making it easier on the scalp. The Genesis range by Kérastase and the Bio Botanical by Sensido range both thicken the hair from the roots, fortifying the strands as they grow.
System 4 Bio-Botanical 3 in 1 Complete Set: Shampoo, Conditioner and Serum
5. Good Porosity (pH 8)
Signs: Colored and treated but shiny, bouncy, and healthy.
Goal: Replenish moisture back to the hair to prevent further damage.
Expert Recommendations: Before and after heat styling, Carbonell recommends adding nourishing treatments or leave-in products to your regimen to protect hair from further damage.
Dry thin hair can get moisture without being limp and heavy with the Milbon Grand Linkage Silky Luxe shampoo, while L’Oréal Professionnel Serie Expert Vitamino Color range has UV filters to prevent color fading. The Kérastase Genesis Heat Protecting Leave-In Treatment for Weakened Hair prevents split ends and frizz without weighing hair down. Thicker dry hair can benefit from the Discipline range by Kérastase.
L’Oréal Professionnel Serie Expert Vitamino Color
Kérastase Genesis Heat Protecting Leave-In Treatment
6. Extreme Porosity (pH 9–10)
Signs: Frequently colored, bleached, rebonded, or chemically treated.
Goal: To restore amino acids or keratin lost during the treatment processes.
Expert Recommendations: Carbonell’s recommendations vary from what treatment caused the sensitization. For thin, damaged or sensitized hair that’s colored, he recommends Kérastase’s Chroma Absolu range while the Première collection is for repairing hair that’s been damaged by chemical treatments.
Thick, damaged or sensitized hair can benefit from the Kerasilk Smoothing Treatment (if colored) and the Resistance line by Kérastase. Rebonded hair can follow up with the Kerafill Smoothing Treatment by Cynos during their in-salon appointments.
7. Severe Damage (pH 10–12)
Signs: Breaking strands, brassiness from severe bleaching and chemical treatments.
Goal: To rebuild the integrity of the hair.
Expert Recommendation: Specialized treatments are necessary to rebuild the integrity of the hair.
Carbonell recommends the Kérastase Première range to remove calcium buildup and help it absorb nourishment after. Absolute Repair Molecular range by L’Oréal rebuilds elastic, stiff hair with peptides. Chroma Absolu Chroma Thermique heat protecting serum by Kérastase reduces frizz while protecting it.
Kérastase Chroma Absolu Chroma Thermique Heat Protecting Serum
Brassy hair is a visible sign that the keratin of the hair is exposed. Carbonell recommends an in-salon keratin treatment by Kerasilk and maintaining its effects with Kerasilk products.
Color-correct with the Milbon Color Gadget Color Shampoo, a dense shampoo with seven colors, from the usual Lavender Purple to Camel Beige for darker hair and vibrant colors like Strawberry Pink and Pistachio Green.
When Products Aren’t Enough
If your hair is falling out—not just breaking—there may be an underlying health issue. “Hair loss means fewer strands. Thinning means finer strands,” clarifies Dr. Fortus. The cause could be stress, hormonal imbalances, thyroid problems, or iron deficiency. If hair care isn’t helping, see a doctor—your body may be telling you something bigger.
Bottom Line
Hair damage doesn’t happen overnight—and neither does healing. The good news? With the right diagnosis and consistent care, even the most stressed-out strands can bounce back stronger than ever.
