A
- 5α-Reductase
- An enzyme that converts testosterone into dihydrotestosterone (DHT). There are two primary isoforms: Type I (found in skin and scalp) and Type II (found in hair follicles and prostate). Inhibiting this enzyme is the primary mechanism of finasteride and dutasteride for treating androgenetic alopecia.
- Acetyl Tyrosine
- A bioavailable ester form of the amino acid tyrosine, which is a precursor in the melanin synthesis pathway. Tyrosine is converted through a biochemical pathway to DOPA and ultimately to melanin. Supporting tyrosine metabolism may help maintain melanocyte activity and hair pigmentation.
- Aldosterone Antagonist
- A drug class that blocks the action of aldosterone, a hormone that regulates sodium and water balance. Spironolactone belongs to this class and is used off-label in women's hair loss treatment primarily for its anti-androgenic properties rather than its diuretic effect.
- Alopecia Areata
- An autoimmune condition in which the immune system attacks hair follicles, causing sudden round or oval patches of hair loss on the scalp or body. Unlike androgenetic alopecia, the follicles are not destroyed, so regrowth is possible. This condition requires dermatologic evaluation and is not treated by minoxidil or finasteride alone.
- Anagen Phase
- The active growth phase of the hair cycle, during which follicle stem cells produce new hair cells. Anagen typically lasts 2–7 years and determines the maximum length a hair can reach. Minoxidil works primarily by prolonging the anagen phase.
- Androgenetic Alopecia
- The most common form of hair loss, driven by genetic sensitivity of hair follicles to dihydrotestosterone (DHT). In men it typically presents as vertex and frontal recession; in women as diffuse thinning. Also known as male- or female-pattern hair loss.
- Anti-Androgen
- A substance that blocks or reduces the effects of androgens (male hormones such as testosterone and DHT) on the body. Spironolactone is an anti-androgen used in women's hair loss treatment to reduce follicle sensitivity to DHT.
- ATP (Adenosine Triphosphate)
- The primary energy currency of cells. In hair follicle cells, ATP production is stimulated by photobiomodulation (LLLT) when red laser light is absorbed by cytochrome c oxidase in mitochondria. Increased ATP supports the metabolic demands of active hair growth during the anagen phase.
B
- Bioavailability
- The proportion of an active ingredient that reaches the target tissue and produces a biological effect. Liposomal delivery systems improve the bioavailability of topical minoxidil by enhancing follicle absorption and reducing systemic exposure.
- Biomimetic Peptides
- Synthetic peptides engineered to mimic naturally occurring signal proteins in the body. In hair treatment, biomimetic peptides can stimulate follicle stem cells, support collagen synthesis in the extracellular matrix, and promote the anagen (growth) phase.
- Biotin (Vitamin B7)
- A B-vitamin involved in keratin production. True biotin deficiency is rare and can cause hair thinning, but in people with normal levels, supplementation has not been shown to improve hair growth. Importantly, high-dose biotin can interfere with thyroid and cardiac blood tests — tell your clinician if you take it.
C
- Capixyl™
- A patented peptide complex (acetyl tetrapeptide-3 + red clover extract) designed to stimulate the extracellular matrix proteins around the hair follicle, improve follicle anchoring, and reduce hair miniaturization. Used in Hair Scripts' proprietary Anti-Gray Serum.
- Cetirizine
- A second-generation antihistamine used in some topical hair loss formulations for its ability to modulate prostaglandin D2 (PGD2) pathway activity and reduce scalp inflammation that may contribute to follicle suppression.
- Compounded Medication
- A prescription medication prepared by a licensed compounding pharmacy to meet a specific patient's needs. Compounded medications allow for customized concentrations, ingredient combinations, and delivery methods that are not available in mass-manufactured FDA-approved drugs. All Hair Scripts prescriptions are compounded.
- Copper Peptides (GHK-Cu)
- A naturally occurring copper complex (glycyl-L-histidyl-L-lysine) that supports collagen synthesis, wound healing, and follicle structural health. In topical hair treatments, copper peptides may improve scalp barrier function and follicle extracellular matrix integrity.
- Cytochrome c Oxidase
- An enzyme in the mitochondrial electron transport chain that serves as a primary chromophore (light-absorbing molecule) in low-level laser therapy (LLLT). When red laser light (650–670nm) is absorbed by cytochrome c oxidase in follicle cell mitochondria, it triggers increased ATP production and cellular metabolism.
D
- DHT (Dihydrotestosterone)
- A potent androgen hormone derived from testosterone by the 5α-reductase enzyme. DHT binds to androgen receptors in hair follicles, causing follicle miniaturization and progressive hair thinning in genetically sensitive individuals. Reducing DHT is the primary goal of finasteride and dutasteride treatment.
- Dutasteride
- A prescription dual 5α-reductase inhibitor that blocks both Type I and Type II isoforms of the enzyme. Reduces serum DHT by up to approximately 95%, making it roughly 3× more potent than finasteride (which only blocks Type II). Available at an adjustable 0.5mg dose. Has a long half-life of approximately 5 weeks. Contraindicated in women of childbearing potential.
E
- Estrogen
- A group of hormones that help keep hair in the anagen (growth) phase longer. When estrogen falls sharply — after childbirth or during perimenopause and menopause — many hairs shift into the resting phase at once, producing noticeable shedding.
- Extracellular Matrix
- The structural network of proteins and molecules surrounding hair follicle cells, including collagen and other connective tissue components. A healthy extracellular matrix supports follicle structural integrity and longevity. Copper peptides (GHK-Cu) and biomimetic peptides can support collagen synthesis in the extracellular matrix.
F
- Ferritin
- The storage form of iron in the body, measured by a blood test. Low ferritin is one of the most common reversible causes of hair shedding — especially in menstruating women — and can trigger telogen effluvium even when hemoglobin is normal. Many clinicians target a ferritin above roughly 40–70 ng/mL to support hair growth.
- Finasteride
- A prescription medication that acts as a selective, competitive inhibitor of Type II 5α-reductase, reducing serum DHT levels by approximately 70%. Available at adjustable 1mg doses, it is clinically proven to increase hair count in androgenetic alopecia. Contraindicated in women of childbearing potential.
- Follicle Miniaturization
- The progressive shrinking of hair follicles caused by DHT-driven androgen sensitivity. Over successive growth cycles, affected follicles produce thinner, shorter, and less pigmented hairs until they stop producing visible hair entirely. This is the primary mechanism of androgenetic alopecia.
G
- Grayverse™
- Hair Scripts' proprietary anti-gray ingredient complex, combining acetyl tyrosine, He Shou Wu (Fo-Ti), niacinamide, Capixyl™, Procapil®, and bioactive peptides to target the melanin synthesis pathway and support melanocyte health.
H
- Hair Transplant
- A surgical procedure relocating DHT-resistant follicles from the back and sides of the scalp into thinning areas. The two main techniques are FUT (strip harvest) and FUE (individual graft extraction). A transplant redistributes existing hair rather than creating new follicles, so medical therapy is usually continued afterward to protect the hair that was not transplanted.
- He Shou Wu (Fo-Ti / Polygonum multiflorum)
- A traditional Chinese medicinal herb (Polygonum multiflorum root extract) historically used to support hair pigmentation and vitality. It is included as an active ingredient in Hair Scripts' proprietary Anti-Gray Serum for its melanocyte-supporting and anti-follicle-aging properties.
- Hormone Replacement Therapy (HRT)
- Treatment that supplements estrogen — often with progesterone — during perimenopause and menopause. By restoring estrogen levels, HRT can reduce menopause-related shedding in some women, though hair benefit is secondary to its primary indications. Note that some progestins are more androgenic than others and may affect hair differently.
- Hypertrichosis
- Unwanted, excessive hair growth in areas not typically affected by androgenetic alopecia, such as the face, cheeks, or hands. A known potential side effect of oral minoxidil due to systemic vasodilatory activity. The effect is generally reversible upon discontinuation or dose reduction.
K
- Ketoconazole
- An antifungal used in medicated shampoos that also carries mild anti-androgenic activity at the scalp. It reduces Malassezia yeast and the inflammation seen in seborrheic dermatitis. Formulations of 1–2% are typically used two to three times weekly as an adjunct to minoxidil and finasteride, not as a standalone treatment.
L
- Latanoprost
- A prostaglandin F2α analog used in topical hair formulations. Originally developed as a glaucoma treatment (where it was noted to increase eyelash growth), latanoprost may support hair density and pigmentation by modulating prostaglandin pathways in the follicle.
- Liposomal Delivery
- A drug delivery system that encapsulates active ingredients (like minoxidil) inside phospholipid vesicles (liposomes). These vesicles fuse with cell membranes, delivering actives directly into the follicle with sustained release over hours. This improves bioavailability while reducing systemic absorption compared to conventional vehicles.
- LLLT (Low-Level Laser Therapy)
- The use of low-level red laser light (650–670nm wavelength) to stimulate hair follicles through photobiomodulation. The light is absorbed by cytochrome c oxidase in follicle cell mitochondria, increasing ATP (cellular energy) production, stimulating follicle metabolism, and promoting the anagen phase. FDA-cleared Class II medical devices. Often used as an adjunct to topical or oral treatments.
- Ludwig Scale
- The standard classification for female-pattern hair loss, from Type I (mild widening of the center part) through Type III (diffuse crown thinning with a preserved frontal hairline). It is the female counterpart to the Norwood scale and is used to stage severity and track treatment response over time.
M
- Melanocyte
- A pigment-producing cell located in the hair follicle bulb. Melanocytes synthesize melanin, which gives hair its color. As follicles age, melanocyte activity declines, leading to gray hair. Factors like oxidative stress and melanocyte apoptosis (cell death) contribute to this process.
- Menopausal Hair Loss
- Thinning that begins or accelerates around menopause, when falling estrogen and progesterone leave androgens relatively unopposed. It usually appears as diffuse crown thinning and a widening part rather than a receding hairline, and often overlaps with female-pattern androgenetic alopecia. Options include topical minoxidil, spironolactone, and in some cases HRT.
- Microneedling
- A procedure using fine needles to create controlled micro-injuries in the scalp, triggering a wound-healing response that releases growth factors and improves absorption of topical treatments. Studies pairing microneedling with topical minoxidil have shown greater regrowth than minoxidil alone. Needle depth, frequency, and sterile technique matter — discuss it with your clinician before starting.
- Minoxidil
- A potassium channel opener originally developed as an oral antihypertensive medication, now the most widely used topical treatment for hair loss. Minoxidil prolongs the anagen (growth) phase, increases follicle size, and promotes scalp vasodilation. It is converted into its active form, minoxidil sulfate, by the SULT1A1 enzyme. Available in topical (5%–10%+) and oral formulations.
- Minoxidil Sulfate
- The active, hair-growth-promoting metabolite of minoxidil. Minoxidil itself is a prodrug — it must be converted into minoxidil sulfate by the SULT1A1 enzyme (primarily in the liver) to exert its therapeutic effect. Individual SULT1A1 enzyme activity is a key predictor of treatment response.
N
- Niacinamide (Vitamin B3)
- A form of vitamin B3 with antioxidant and anti-inflammatory properties. In hair care, niacinamide supports scalp barrier function, improves blood flow to follicles, and helps mitigate oxidative stress that contributes to follicle aging and pigment loss.
- Norwood Scale
- The standard seven-stage classification for male-pattern hair loss, describing progression from a mature hairline (Stage I–II) through frontal and vertex recession to extensive loss leaving only a horseshoe rim (Stage VII). Clinicians use it to stage severity, set realistic expectations, and measure treatment response. The female counterpart is the Ludwig scale.
O
- Oxidative Stress
- Cellular damage caused by an imbalance between reactive oxygen species (free radicals) and the body's antioxidant defenses. In hair follicles, oxidative stress can damage melanocytes, accelerate follicle aging, and contribute to both hair graying and hair loss. Topical antioxidants and ingredients like niacinamide (Vitamin B3) help mitigate oxidative follicle damage.
P
- Penetration Enhancer
- An ingredient added to a topical formulation to increase the absorption of the primary active ingredients through the scalp barrier and into the hair follicle. Retinoic acid and certain peptide formulations act as penetration enhancers in Hair Scripts' custom topical serums.
- Perimenopause
- The transitional years before menopause — often beginning in the early-to-mid forties — when estrogen and progesterone fluctuate unpredictably. These swings commonly trigger increased shedding and gradual thinning before periods stop entirely, and hair changes are frequently one of the earliest signs a woman notices.
- Photobiomodulation (PBM)
- The biological mechanism by which low-level laser light stimulates cellular activity. In hair treatment, red wavelength light (650–670nm) is absorbed by mitochondrial chromophores in follicle cells, triggering increased ATP production, reduced inflammation, and enhanced cellular metabolism that supports hair growth.
- Phospholipid Vesicles
- Microscopic spherical structures composed of phospholipid bilayers, commonly known as liposomes. In liposomal drug delivery, these vesicles encapsulate active ingredients and fuse with cell membranes to deliver their payload directly into target cells — in this case, hair follicle cells.
- Post-Finasteride Syndrome (PFS)
- A reported but not universally recognized condition in which patients experience persistent sexual, neurological, and physical side effects after discontinuing finasteride. While rare, it is an important consideration in informed consent and shared decision-making when prescribing 5α-reductase inhibitors.
- Postpartum Hair Loss
- A common form of telogen effluvium occurring roughly two to four months after childbirth. High estrogen during pregnancy holds hair in the growth phase; when estrogen drops after delivery, those retained hairs shed together — dramatic, but temporary. It usually resolves on its own by six to twelve months. Shedding that persists past a year warrants evaluation for low ferritin or thyroid issues.
- Potassium Channel Opener
- A classification of drug that opens potassium channels in cell membranes, increasing membrane permeability and intracellular signaling. Minoxidil is a potassium channel opener — this mechanism (rather than vasodilation alone) is now understood to be its primary mechanism for prolonging the anagen (growth) phase of the hair cycle.
- Procapil®
- A patented cosmetic ingredient combining apigenin, oleanolic acid, and biotinoyl tripeptide-1. Designed to improve follicle anchoring, reduce hair shedding, and support the extracellular matrix around the hair bulb. Found in Hair Scripts' proprietary Anti-Gray Serum.
- Prostaglandin D2 (PGD2)
- A prostaglandin found at elevated levels in balding scalp tissue. PGD2 pathway activity has been implicated in the inhibition of hair growth. Ingredients like cetirizine (a second-generation antihistamine) and latanoprost (a prostaglandin F2α analog) are used to modulate PGD2-related pathways in topical hair loss formulations.
- PRP (Platelet-Rich Plasma)
- A procedure in which a small volume of the patient's own blood is spun in a centrifuge to concentrate platelets, and the resulting plasma is injected into the scalp. The concentrated growth factors are intended to stimulate follicles and extend the anagen phase. Evidence is promising, but protocols vary widely between providers and results typically require repeat sessions.
R
- Retinoic Acid
- A derivative of vitamin A used in topical hair loss formulations as a penetration enhancer. Retinoic acid increases scalp permeability and cell turnover, improving the absorption of co-applied active ingredients like minoxidil and finasteride into the follicle.
- Rosemary Oil
- A plant-derived essential oil studied as a natural option for androgenetic alopecia. One frequently cited trial found it comparable to 2% minoxidil at six months with less scalp itching — though the study was small, and the effect is generally slower and milder than prescription therapy. Always dilute in a carrier oil to avoid irritation.
S
- Saw Palmetto
- An extract of the Serenoa repens berry that acts as a weak natural 5α-reductase inhibitor, mildly reducing conversion of testosterone to DHT. It is considerably less potent than finasteride and the supporting evidence is limited, but it is sometimes chosen by people who prefer to avoid prescription DHT blockers.
- Seborrheic Dermatitis
- A common inflammatory scalp condition causing greasy scaling, redness, and flaking, driven partly by Malassezia yeast. The resulting inflammation and scratching can worsen shedding, so controlling it — often with a medicated shampoo such as ketoconazole — is frequently part of a complete hair loss plan.
- Spironolactone
- An aldosterone antagonist with anti-androgenic properties. It blocks androgen receptors and reduces adrenal androgen production, reducing the sensitivity of hair follicles to DHT and testosterone. Used off-label for female androgenetic alopecia and hormonal hair loss in women. Contraindicated during pregnancy. Dosing typically starts at 50–100mg.
- SULT1A1 Enzyme
- Sulfotransferase 1A1 — the liver enzyme responsible for converting minoxidil into its active form, minoxidil sulfate. Individual variations in SULT1A1 enzyme activity are a key biological marker that predicts how well a person will respond to minoxidil treatment. Hair Scripts offers an at-home SULT1A1 response test before prescribing.
- Systemic Absorption
- The degree to which a topically applied medication enters the bloodstream and circulates throughout the body. Higher systemic absorption increases the risk of side effects. Liposomal delivery systems and topical formulations are designed to minimize systemic absorption while maximizing follicle-targeted delivery.
T
- Telogen Effluvium
- Temporary diffuse shedding in which a stressor pushes an abnormally large share of follicles into the telogen (resting) phase at once. Common triggers include childbirth, surgery, severe illness, rapid weight loss, low ferritin, thyroid disease, and major emotional stress. Shedding typically starts two to three months after the trigger and resolves once the underlying cause is corrected.
- Telogen Phase
- The resting phase of the hair growth cycle, lasting approximately 2–4 months. During telogen, the hair is fully formed but no longer growing. At the end of telogen, the hair sheds (telogen effluvium) and the follicle re-enters anagen to begin a new growth cycle. Stress, illness, and hormonal changes can push follicles prematurely into telogen.
- Terminal Hair
- Thick, long, pigmented hair — normal scalp hair — as opposed to fine vellus hair. The central process in androgenetic alopecia is miniaturization: terminal hairs progressively convert into vellus-like hairs. Treatment success is often measured by the reverse — pushing vellus hairs back toward terminal thickness.
- Traction Alopecia
- Hair loss caused by chronic pulling from tight hairstyles — braids, weaves, extensions, tight ponytails, or locs. It characteristically affects the hairline and temples. In early stages it is fully reversible, but sustained tension eventually scars the follicle and the loss becomes permanent. Loosening styling early is the single most effective intervention.
- Trichologist
- A trained specialist in trichology — the science and study of hair and scalp health. Unlike dermatologists, trichologists focus exclusively on hair and scalp disorders. At Hair Scripts, every patient is evaluated by a licensed trichologist who builds a personalized treatment protocol based on individual biology, scalp assessment, and diagnostic testing.
- TRP-2 (Dopachrome Tautomerase)
- An enzyme involved in the melanin synthesis pathway that helps convert dopachrome to DOPA during pigment production. Supporting TRP-2 activity is one mechanism by which anti-gray treatments aim to maintain melanocyte function and delay pigment loss in the hair follicle.
V
- Vasodilation
- The widening of blood vessels, which increases blood flow and nutrient delivery to tissues. Minoxidil acts as a vasodilator, increasing blood flow to hair follicles. However, its hair-growth effects are now understood to be primarily driven by potassium channel opening and anagen phase prolongation, rather than vasodilation alone.
- Vellus Hair
- Short, fine, lightly pigmented hair — sometimes called peach fuzz. In androgenetic alopecia, DHT drives terminal hairs to miniaturize into vellus-like hairs, which is why thinning areas first look wispy rather than bald. Effective treatment works to reverse this.
Compounded medications are not FDA-approved. Individual results may vary. This glossary is for informational purposes only and does not constitute medical advice. Consult a licensed clinician before starting any treatment.