Minoxidil with tretinoin, ketoconazole, latanoprost and more: what each add-on is for

If you have looked into prescription hair sprays, you have seen long ingredient lists: minoxidil plus tretinoin, ketoconazole, latanoprost, fluocinolone, finasteride, biotin, or melatonin. The idea is that each add-on helps in a different way. This guide goes through them one at a time and says plainly what each is thought to do and what the research does, and does not, show.

One point up front: the studies below each tested one ingredient, or minoxidil plus one other. None tested the exact four- or five-ingredient compounded sprays sold today. Evidence for each part does not add up to evidence for the whole.

The base: minoxidil

Every spray in this guide is built on topical minoxidil, the only one of these ingredients with substantial trial evidence for female pattern hair loss. A Cochrane review found that women using minoxidil were about twice as likely as those on placebo to report moderate to marked regrowth ^[2]. For the full picture, including how long it takes and what happens if you stop, see minoxidil for women.

One detail from the over-the-counter label is worth knowing. The women's minoxidil foam label says not to use it if you use other medicines on the scalp ^[1]. Prescription combinations are, by design, other medicines on the scalp. That is a decision your prescribing clinician makes with you, not one to make on your own by layering products.

Tretinoin: helping minoxidil work

Tretinoin is a topical retinoid ^[5]. In hair sprays, it is there to help minoxidil, not to grow hair by itself.

What it is thought to do. Minoxidil only works after enzymes in the follicle, called sulfotransferases, convert it to its active form ^[5]. People with low enzyme activity tend to respond poorly. In one study, applying tretinoin for 5 days increased this enzyme activity, and 43% of people predicted to be non-responders to minoxidil were converted to predicted responders ^[5]. Tretinoin also increases absorption: a 2026 review notes nearly a threefold increase in minoxidil absorbed into the body when tretinoin cream is applied first ^[3].

What the evidence shows. The same review describes clinical data on the combination as minimal ^[3]. Its one randomized trial, in 31 men, found once-daily 5% minoxidil plus 0.01% tretinoin worked about as well as twice-daily 5% minoxidil, with similar rates of itching and irritation ^[4]. The review concludes the evidence does not support the combination as a first choice, but that tretinoin may be considered as an add-on, especially for people who have not responded to minoxidil, weighed against more irritation ^[3].

Ketoconazole: the antifungal

Ketoconazole is an antifungal. As a cream, it is FDA-approved for fungal skin infections and seborrheic dermatitis ^[8].

What it is thought to do. Researchers have proposed that scalp yeast (Malassezia) may feed inflammation around hair follicles in pattern hair loss, and ketoconazole acts against that yeast and has some anti-inflammatory activity ^[7].

What the evidence shows. A 1998 study compared 2% ketoconazole shampoo with minoxidil and found improvements in hair density and the share of growing hairs that were similar between the two, while its authors said larger controlled studies were needed ^[7]. A 2020 systematic review found five human studies with 318 participants that reported thicker hair shafts and some clinical improvement, called ketoconazole a promising add-on, and said randomized controlled trials are needed ^[6]. That is a small, early evidence base.

Side effects. In clinical trials of ketoconazole cream, 5.0% of patients reported side effects, mainly irritation, itching, and stinging, compared with 2.4% on placebo ^[8].

Latanoprost: the eyelash connection

Latanoprost is a glaucoma eye drop. Its prescribing label notes that it gradually makes eyelashes longer, thicker, and more numerous ^[10]. Researchers tried it on the scalp because of that effect on lashes ^[9].

What the evidence shows. The main scalp study was a 24-week pilot in 16 young men with mild pattern hair loss, each treating one small scalp area with 0.1% latanoprost and another with placebo ^[9]. Hair density rose on the latanoprost area compared with the placebo area ^[9]. The authors noted the results may not apply to other groups ^[9]. We did not find a comparable controlled trial of scalp latanoprost in women with pattern hair loss.

A safety note. On the eye, latanoprost can darken the iris, eyelid skin, and lashes, and iris darkening is likely to be permanent ^[10]. Keep any latanoprost spray away from your eyes.

Fluocinolone: a steroid for scalp irritation

Fluocinolone acetonide is a topical corticosteroid. As a 0.01% scalp oil, it is FDA-approved to treat scalp psoriasis in adults ^[11]. In a hair spray, it is meant to calm the scalp irritation that minoxidil and tretinoin can cause.

Irritation is a real issue with minoxidil. A review of patch-tested cases found minoxidil itself, and the common solvent propylene glycol, were the main causes of allergic reactions to minoxidil products ^[18].

What the label says about steroids. The fluocinolone scalp oil label tells users to stop once the condition is controlled, and to contact a clinician if there is no improvement within 2 weeks ^[11]. Topical steroids can be absorbed and, with large areas, prolonged use, or covered skin, can suppress the body's own steroid hormones ^[11]. Local side effects can include skin thinning (atrophy), stretch marks, visible small blood vessels, burning, itching, folliculitis, and lightening of the skin, and some may be irreversible ^[11]. Steroids near the eyes may raise the risk of glaucoma and cataracts ^[11].

What the evidence shows for hair. We did not find a trial testing whether adding fluocinolone to minoxidil improves regrowth or tolerability in women. Its role in these sprays is to manage irritation, and because they are used daily for the long term, the steroid warnings above are worth discussing with your clinician.

Finasteride: blocking DHT

Finasteride blocks the conversion of testosterone to DHT, a stronger androgen ^[16]. In a 24-week trial of 30 postmenopausal women, 0.25% topical finasteride plus 3% minoxidil improved hair thickness more than 3% minoxidil alone, and blood DHT levels fell ^[20].

Finasteride is contraindicated in women who are or may become pregnant, because it may cause abnormal genitals in a male fetus ^[16]. The FDA has also warned about compounded topical finasteride, including side effects that persisted after stopping ^[17]. Read more in topical finasteride for women.

Biotin: popular, little evidence

Biotin is a B vitamin heavily marketed for hair, skin, and nails. A review of the research found 18 reported cases where biotin helped hair or nails, and in every one, the person had an underlying condition, such as a deficiency ^[12]. The authors concluded there is not enough evidence for biotin in healthy people ^[12]. We found no trial of topical biotin on the scalp for pattern hair loss.

The lab test warning. The FDA warns that biotin, often found in supplements, can significantly interfere with certain lab tests and cause incorrect results that may go undetected ^[13]. It has received reports of falsely low troponin results, a blood test used to diagnose heart attacks ^[13]. That warning concerns biotin in the body, mostly from supplements; how much biotin a scalp spray adds to your blood is not known. To be safe, tell any clinician or lab that you use a biotin product before blood tests.

Melatonin: one small trial in women

Melatonin is mostly studied as an oral supplement for sleep ^[15]. On the scalp, it has been tested in one small randomized trial in women ^[14]. Forty women with pattern or diffuse hair loss applied 0.1% melatonin or a placebo solution once daily for 6 months ^[14]. Melatonin increased the share of hairs in the growth phase in some measured areas but not others, and blood melatonin rose but stayed within the normal nighttime range ^[14]. The authors called it a pilot study ^[14].

A 2024 review of topical melatonin studies concluded most did not clearly show a hair growth benefit, apart from that one trial suggesting a possible role in some forms of hair loss in women, and that more research is needed ^[15].

The evidence at a glance

What is in WarriorBabe Health's hair sprays

• Minoxidil + Tretinoin Hair Spray: minoxidil, finasteride, and tretinoin, applied daily at bedtime.
• Minoxidil + Ketoconazole Hair Spray: minoxidil, finasteride, latanoprost, and ketoconazole, applied daily.
• Minoxidil + Fluocinolone Hair Spray: minoxidil, tretinoin, fluocinolone, and finasteride, applied daily to a clean, dry scalp.
• Minoxidil + Biotin Hair Spray: minoxidil, tretinoin, fluocinolone, biotin, and melatonin. It contains no finasteride.

Strengths are set on your prescription. All four are compounded by a licensed pharmacy under your clinician's prescription. Compounded drugs are not FDA-approved, which means the FDA does not review their safety, effectiveness, or quality before they are marketed ^[19]. You can compare them on our hair treatments page.

Before starting, tell your clinician if you are or could become pregnant, have heart disease or blood pressure concerns, have a history of depression or anxiety, or have lab tests coming up. To see whether one of these sprays might suit you, take the 2-minute quiz. For background on causes, see hair thinning after menopause.

This article is for general information. It is not medical advice and does not replace a visit with a licensed clinician who knows your history. Do not start, stop or change a medication without talking to your clinician. If you think you are having a medical emergency, call 911.