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Systematic (IUPAC) name
6-Piperidin-1-ylpyrimidine-2,4-diamine 3-oxide
Clinical data
Trade names Rogaine
AHFS/Drugs.com monograph
  • C
  • P(UK) for topical use, otherwise POM. Cannot be prescribed on the NHS.
Oral / topical
Pharmacokinetic data
Metabolism Primarily hepatic
Half-life 4.2 h
Excretion renal
38304-91-5 YesY
C02DC01 D11AX01
PubChem CID 4201
IUPHAR ligand 4254
DrugBank DB00350 N
ChemSpider 10438564 YesY
UNII 5965120SH1 N
KEGG D00418 N
Chemical data
Formula C9H15N5O
209.251 g/mol
 N (what is this?)  (verify)

Minoxidil is an antihypertensive vasodilator medication. It also slows or stops hair loss and promotes hair regrowth in some people. Now off-patent, it is available over-the-counter for the treatment of androgenic alopecia.

Medical uses[edit]

Minoxidil, applied topically, is widely used for the treatment of hair loss. It is effective in helping promote hair growth in both males and females with androgenic alopecia.[1] About 40% of men experience hair regrowth after 3–6 months.[2] Minoxidil must be used indefinitely for continued support of existing hair follicles and the maintenance of any experienced hair regrowth.[3][4] It is the only topical product that is FDA approved for androgenic hair loss.[1]

Its effect in people with alopecia areata is unclear.[5]

Side effects[edit]

Minoxidil is generally well tolerated, but common side effects include burning or irritation of the eye, itching, redness or irritation at the treated area, as well as unwanted hair growth elsewhere on the body. Exacerbation of hair loss/alopecia has been reported.[6][7] Users should discontinue treatment and seek medical attention right away if they experience any of the following serious side effects: severe allergic reactions (e.g. rash, hives, itching, difficulty breathing, tightness in the chest, or swelling of the mouth, face, lips, or tongue), chest pain, dizziness, fainting, tachycardia (rapid heartbeat), sudden and unexplained weight gain, or swelling of the hands and feet.[8] Temporary hair loss is a common side effect of minoxidil treatment.[9] Manufacturers note that minoxidil-induced hair loss is a common side effect and describe the process as "shedding".

Alcohol and propylene glycol present in some topical preparations may dry the scalp, resulting in dandruff and contact dermatitis.[10] Some formulations of minoxidil substitute lipid Nanosomes in order to reduce contact dermatitis from the alcohol and propylene glycol vehicle.[11][12]

Side effects of oral minoxidil may include swelling of the face and extremities, rapid and irregular heartbeat, lightheadedness, cardiac lesions, and focal necrosis of the papillary muscle and subendocardial areas of the left ventricle.[7] There have been cases of allergic reactions to minoxidil or the non-active ingredient propylene glycol, which is found in some topical minoxidil formulations. Pseudoacromegaly is an extremely rare side effect reported with large doses of oral minoxidil.[13]

Minoxidil is highly toxic to cats.[14][15]

Mechanism of action[edit]

The mechanism by which minoxidil promotes hair growth is not fully understood. Minoxidil is a potassium channel opener, causing hyperpolarization of cell membranes. Minoxidil is less effective when there is a large area of hair loss. In addition, its effectiveness has largely been demonstrated in younger men who have experienced hair loss for less than 5 years. Minoxidil use is indicated for central (vertex) hair loss only.[16] Minoxidil is also a vasodilator.[17] Hypothetically, by widening blood vessels and opening potassium channels, it allows more oxygen, blood, and nutrients to the follicle. This may cause follicles in the telogen phase to shed, which are then replaced by thicker hairs in a new anagen phase. Minoxidil is a pro-drug activated by sulfation via the sulfotransferase (SULT1A1). Several studies demonstrated that the activity of sulfotransferase in hair follicles predict minoxidil response in the treatment of hair loss.[18][19][20] Two clinical studies are being conducted in the US for a medical device that may allow patients to determine if they are likely to fail minoxidil therapy.[21]


Originally, minoxidil was used exclusively as an oral drug (with the trade name 'Loniten') to treat high blood pressure. However, it was discovered to have an interesting side effect: hair growth.[22] Minoxidil may cause increased growth or darkening of fine body hairs, or in some cases, significant hair growth. When the medication is discontinued, the hair loss will return to a normal rate within 30 to 60 days. Upjohn Corporation produced a topical solution that contained 2% minoxidil to be used to treat baldness and hair loss, under the brand name Rogaine in the United States and Canada, and Regaine in Europe and the Asia-Pacific. The patent on minoxidil expired February 11, 1996. Treatments usually include a 5% concentration solution that is designed for men, and a 2% concentration solution for women.[23] While the drug is available in the United Kingdom, it cannot be prescribed on the NHS, so patients must either buy it over-the-counter, or have a private prescription for it.[24]


Minoxidil needs to be applied twice daily, and may be used indefinitely for continued support of existing hair follicles and the maintenance of any experienced hair regrowth. To achieve maximum effect, the solution should be in contact with the scalp for at least 4 hours before allowing hair to get wet.[25] Minoxidil stimulates hair follicles and growth, but does not reduce dihydrotestosterone (DHT) or the enzyme responsible for its accumulation around the hair follicle, 5-alpha reductase, which is the primary mediator of male pattern baldness in genetically susceptible individuals.[26] Therefore, when treatment is stopped, the DHT has its expected effect of shrinking and ultimately destroying the genetically predisposed hair follicles. There are multiple types of minoxidil applications: dropper, foam and spray.

Trade names[edit]

Minoxidil is marketed under many trade names, including Amexidil, Avacor Physician's Formulation, Avogain, Keranique, Kirkland Signature (Costco's private label brand), Lipogaine, Loniten (oral), Mintop,[27] Neocapil, Obabo, Regaine, Regenepure, Rogaine, Tugain,[27] Up & Up (Target's private label brand), and Vanarex.

See also[edit]


  1. ^ a b Varothai, S; Bergfeld, WF (July 2014). "Androgenetic alopecia: an evidence-based treatment update.". American journal of clinical dermatology 15 (3): 217–30. PMID 24848508. 
  2. ^ "Clinical utility and validity of minoxidil response testing in androgenetic alopecia.". Dermatol Ther 28 (1): 13–6. doi:10.1111/dth.12164. PMID 25112173. 
  3. ^ Olsen, Elise A.; Dunlap, Frank E.; Funicella, Toni; Koperski, Judith A.; Swinehart, James M.; Tschen, Eduardo H.; Trancik, Ronald J. (2002). "A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in the treatment of androgenetic alopecia in men". Journal of the American Academy of Dermatology 47 (3): 377–385. doi:10.1067/mjd.2002.124088. ISSN 0190-9622. 
  4. ^ Olsen, Elise A.; Weiner, Madeline S.; Amara, Ingrid A.; DeLong, Elizabeth R. (1990). "Five-year follow-up of men with androgenetic alopecia treated with topical minoxidil". Journal of the American Academy of Dermatology 22 (4): 643–646. doi:10.1016/0190-9622(90)70089-Z. ISSN 0190-9622. 
  5. ^ Hordinsky, M; Donati, A (July 2014). "Alopecia areata: an evidence-based treatment update.". American journal of clinical dermatology 15 (3): 231–46. PMID 25000998. 
  6. ^ http://www.drugs.com/sfx/rogaine-side-effects.html
  7. ^ a b "Minoxidil Official FDA information, side effects and uses". Drugs.com. 
  8. ^ Rogaine Side Effects | Drugs.com
  9. ^ FAQs | Rogaine
  10. ^ "Dandruff and Seborrheic Dermatitis". Medscape.com. Retrieved 2009-10-09. 
  11. ^ Balakrishnan P, Shanmugam S, Lee WS, Lee WM, Kim JO, Oh DH, Kim DD, Kim JS, Yoo BK, Choi HG, Woo JS, Yong CS (1 February 2009). "Formulation and in vitro assessment of minoxidil Nanosomes for enhanced skin delivery". International Journal of Phermaceutics 377 (1-2): 1–8. doi:10.1016/j.ijpharm.2009.04.020. PMID 19394413. 
  12. ^ Padois K, Cantiéni C, Bertholle V, Bardel C, Pirot F, Falson F (16 June 2011). "Solid lipid nanoparticles suspension versus commercial solutions for dermal delivery of minoxidil". International Journal of Pharmaceutics 416 (1): 300–304. doi:10.1016/j.ijpharm.2011.06.014. PMID 21704140. 
  13. ^ Nguyen, K.; Marks Jr, J. (2003). "Pseudoacromegaly induced by the long-term use of minoxidil". Journal of the American Academy of Dermatology 48 (6): 962–965. doi:10.1067/mjd.2003.325. PMID 12789195. 
  14. ^ Camille DeClementi; Keith L. Bailey; Spencer C. Goldstein; Michael Scott Orser (December 2004). "Suspected toxicosis after topical administration of minoxidil in 2 cats". Journal of Veterinary Emergency and Critical Care 14 (4): 287–292. doi:10.1111/j.1476-4431.2004.04014.x. 
  15. ^ "Minoxidil Warning". ShowCatsOnline.com. Retrieved 2007-01-18. Very small amounts of Minoxidil can result [in] serious problems or death 
  16. ^ Scow, DT; Nolte, RS; Shaughnessy, AF (April 1999). "Medical treatments for balding in men". Am Fam Physician 59 (8): 2189–94. PMID 10221304. 
  17. ^ Vasodilators | MayoClinic.com
  18. ^ Goren, A.; Shapiro, J.; Roberts, J.; McCoy, J.; Desai, N.; Zarrab, Z.; Pietrzak, A.; Lotti, T. (2015). "Clinical utility and validity of minoxidil response testing in androgenetic alopecia". Dermatologic Therapy 28: 13. doi:10.1111/dth.12164.  edit
  19. ^ Roberts, J.; Desai, N.; McCoy, J.; Goren, A. (2014). "Sulfotransferase activity in plucked hair follicles predicts response to topical minoxidil in the treatment of female androgenetic alopecia". Dermatologic Therapy 27 (4): 252. doi:10.1111/dth.12130.  edit
  20. ^ Goren, A.; Castano, J. A.; McCoy, J.; Bermudez, F.; Lotti, T. (2014). "Novel enzymatic assay predicts minoxidil response in the treatment of androgenetic alopecia". Dermatologic Therapy 27 (3): 171. doi:10.1111/dth.12111.  edit
  21. ^ Minoxidil Response Testing in Males With Androgenetic Alopecia
  22. ^ MINOXIDIL - ORAL (Loniten) side effects, medical uses, and drug interactions | MedicineNet
  23. ^ "Grant v. Pharmacia & Upjohn Co.". Retrieved 2009-01-17. 
  24. ^ Drug Tariff, 2009/04/11[full citation needed]
  25. ^ minoxidil (Rogaine) - drug class, medical uses, medication side effects, and drug interactions by MedicineNet.com
  26. ^ American Hair Loss Association | Men's Hair Loss | Causes of Hair Loss
  27. ^ a b Sharma, Sanchita (25 February 2012). "Hair transplants get a leg up". Hindustan Times. Retrieved 3 May 2015. 

External links[edit]