The most effective option depends on what’s causing your hair loss, but the strongest evidence supports two treatments: minoxidil and finasteride. Beyond those, certain vitamins, minerals, and natural supplements can meaningfully support hair growth, especially if you have an underlying deficiency. Here’s what actually works, what the evidence looks like, and what to realistically expect.
Minoxidil: The Most Accessible Option
Minoxidil is the only topical hair growth treatment approved by the FDA, available over the counter in 2% and 5% formulations. It works by increasing blood flow to hair follicles and extending the active growth phase of the hair cycle. In clinical trials, 5% minoxidil foam increased non-vellus hair count (the thicker, visible hairs that matter cosmetically) by 13.4% over 16 weeks compared to 3.4% for placebo.
You apply it directly to thinning areas once or twice daily. Most people start noticing new growth between three and six months in, and some experience a temporary increase in shedding during the first few weeks. This early shedding is actually a sign that dormant follicles are being pushed into a new growth cycle. Minoxidil works for both men and women, though the 5% concentration is more commonly recommended for men and the 2% for women. The catch: you need to keep using it. Stopping treatment gradually reverses the gains.
An oral form of minoxidil, prescribed off-label by some dermatologists, has shown even stronger results. At 5 mg daily, total hair count increased by about 19% and non-vellus hair count by nearly 24% over 24 weeks.
Finasteride for Hormonal Hair Loss
Finasteride targets the root hormonal cause of the most common type of hair loss in men: androgenetic alopecia, or male pattern baldness. It works by blocking an enzyme that converts testosterone into dihydrotestosterone (DHT), the hormone responsible for shrinking hair follicles over time. At a standard dose, finasteride suppresses scalp DHT levels by up to 65% within about six weeks.
Clinical trials show finasteride increases non-vellus hair count by about 9% over 12 months, which sounds modest compared to minoxidil’s numbers but reflects a fundamentally different mechanism. While minoxidil stimulates follicles directly, finasteride slows and partially reverses the miniaturization process that causes permanent thinning. Many dermatologists recommend using both together for the best results.
Finasteride does carry potential side effects that deserve consideration: decreased libido, erectile dysfunction, breast tenderness, and in rare cases, depression. These side effects resolve for most men after stopping the medication, though a small subset reports persistent symptoms. Finasteride is not approved for women of childbearing age because it can cause birth defects.
Spironolactone for Women
For women experiencing pattern hair loss, spironolactone is the most commonly prescribed off-label option. Originally developed as a blood pressure medication, it blocks DHT from binding to androgen receptors in hair follicles, reducing the follicle shrinkage that leads to thinning. Typical doses range from 100 to 200 mg daily, though some providers start as low as 25 mg and increase gradually.
Spironolactone is only used in women because of its anti-androgenic effects, and it’s often combined with topical minoxidil for a two-pronged approach.
Vitamins and Minerals That Actually Matter
Supplements won’t regrow hair that’s been lost to genetic pattern baldness. But if your hair loss is driven by a nutritional deficiency, correcting it can stop the shedding and restore normal growth. The three nutrients most directly linked to hair loss are iron, vitamin D, and biotin.
Iron and Ferritin
Low iron stores are one of the most common and overlooked causes of excessive hair shedding, particularly in women. Your body prioritizes iron for essential functions like oxygen transport, and hair follicles are among the first things to suffer when levels drop. Research has identified a ferritin level (the protein that stores iron) around 24 to 25 ng/mL as a diagnostic threshold, below which shedding becomes significantly more likely. Many dermatologists prefer to see ferritin above 40 or even 70 ng/mL before ruling out iron as a contributor. If you’re losing hair diffusely across your scalp rather than in a distinct pattern, a ferritin test is worth requesting.
Vitamin D
Low vitamin D levels are strongly correlated with both the presence and severity of hair loss. In studies of alopecia patients, those with a single patch of hair loss had average vitamin D levels around 19 ng/mL, while those with multiple patches averaged just 12 ng/mL. The correlation is clear: lower vitamin D, worse hair loss. Since vitamin D plays a role in the creation of new hair follicles and the cycling of existing ones, maintaining adequate levels (generally above 30 ng/mL) supports healthy growth. A simple blood test can tell you where you stand.
Biotin
Biotin is the most heavily marketed hair supplement, but true biotin deficiency is uncommon in people eating a varied diet. If you are deficient, supplementation can improve hair quality. If you’re not, extra biotin is unlikely to make a noticeable difference. One important caution: high-dose biotin supplements (often sold at 5,000 to 10,000 mcg) can interfere with lab tests, including cardiac troponin tests used to diagnose heart attacks. The FDA has specifically warned that biotin interference can produce falsely low results on critical blood tests. If you’re taking biotin, stop it at least 72 hours before any blood work.
Natural and Over-the-Counter Supplements
Rosemary Oil
Rosemary oil is the best-studied natural alternative. A six-month head-to-head trial compared rosemary oil applied to the scalp against 2% minoxidil, and both groups saw a significant increase in hair count with no statistically significant difference between them. That’s a notable finding for a plant-based option. The main downside is scalp irritation in some users, and consistency matters: results took six months to appear, with no meaningful change at three months.
Saw Palmetto
Saw palmetto works through a mechanism similar to finasteride, blocking both forms of the enzyme that produces DHT and reducing DHT’s ability to bind to androgen receptors by nearly 50%. Five randomized clinical trials and two prospective studies have shown positive effects at doses between 100 and 320 mg daily. It’s a milder option than finasteride, with fewer reported side effects, though its effects are also generally less dramatic. Some people use it as a first step before considering prescription medication, or as a complement to topical treatments.
Collagen Peptides
Oral collagen supplements have shown some promising early results for hair. In a 12-week trial, participants taking hydrolyzed collagen saw a 27.6% increase in total hair count compared to placebo, and about 67% of participants reported their hair felt thicker versus 44% in the placebo group. Expert grading of hair appearance improved by 32% in the collagen group compared to 9% for placebo. These results are encouraging, though the hair count difference didn’t reach statistical significance, meaning larger studies are needed to confirm the effect.
Why Results Take Months
Hair growth is cyclical. Each follicle moves independently through three phases: an active growth phase that lasts several years, a brief transition phase, and a resting phase that can last up to a year on the scalp. At any given time, 10 to 15% of your scalp hairs are resting. When you start a new treatment, it needs to push resting follicles back into active growth and then give those hairs enough time to grow to a visible length.
This is why virtually every effective hair treatment requires three to six months of consistent use before you can judge whether it’s working. Taking progress photos in the same lighting every four weeks is more reliable than checking the mirror daily, because the changes are gradual enough to miss in real time. If you haven’t seen any improvement after six months of consistent use, that treatment likely isn’t the right fit, and it’s worth exploring other options or combinations.
Combining Treatments for Better Results
The strongest outcomes typically come from stacking treatments that work through different mechanisms. For men, the classic combination is topical minoxidil (stimulating follicles directly) plus finasteride or saw palmetto (reducing DHT). For women, minoxidil combined with spironolactone addresses both stimulation and hormonal factors. Adding a nutritional foundation, correcting any iron or vitamin D deficiency, ensuring adequate protein intake, supports whatever else you’re doing.
Rosemary oil can be layered in as well, though you’ll want to apply it at a different time of day than minoxidil to avoid diluting either product. Collagen and saw palmetto are oral supplements that won’t interfere with topical treatments. The key principle is straightforward: address the cause of your hair loss (hormonal, nutritional, or both) while simultaneously stimulating the follicles you still have.