Side effects are uncommon at the low doses used to treat hair loss. The largest study looking at side effects (Vañó-Galván et al. 2021) showed that in 943 women and 461 men, 2.5% of women and 0.5% of men had to stop treatment because of a side effect. In non-clinical studies in a variety of species, minoxidil induces several types of cardiac lesions including necrotic and haemorrhagic lesions of the myocardium and papillary muscles, and cardiac hypertrophy and dilation. These changes occur only in the context of profound hypotension and tachycardia and reflect haemodynamic and/or hypoxic stress rather than direct cytotoxicity. As greater experience with the drug has accumulated, it has become apparent that these cardiac lesions do not occur in humans treated with minoxidil.

a b Kuntzman G (2001). Hair!: Mankind's Historic Quest to End Baldness. Random House Publishing Group. p.172. ISBN 978-0679647096 . Retrieved May 11, 2015. (Google Books) Otomo S (March 2002). "[Hair growth effect of minoxidil]". Nihon Yakurigaku Zasshi. Folia Pharmacologica Japonica. 119 (3): 167–174. doi: 10.1254/fpj.119.167. PMID 11915519. Uncommon side effects include – nightmares, insomnia, pericarditis, skin rashes, nausea, vomiting, and breast tenderness. In 2021, we got the first study that directly compared the 5% to the 10% minoxidil strength ( 4). A research team out of Egypt recruited 90 men with all grades of hair loss. They treated them with either 5% minoxidil, 10% minoxidil, or a placebo. Treatment lasted 36 weeks. Efficacy Here is a look at the changes in the participants’ nonvellus hair counts over the course of the trial:don’t wash your hair, go swimming, or allow your hair to get wet in the rain for at least four hours after using Minoxidil

Dosage requirements may be lower in dialysis patients. Minoxidil is removed from the blood by dialysis, but its pharmacological action, once established is not reversed. Therefore haemodialysis patients should take minoxidil either after or at least two hours before dialysis. Aside from minoxidil, the only other FDA-approved treatment for male pattern hair loss is finasteride. The approved version for baldness is a 1mg daily pill ( 10). Scientists first developed minoxidil in the 1950s. Upjohn, the company that manufactured it, originally hoped to sell it for the treatment of ulcers but eventually marketed it as a vasodilator. The key thing to bear in mind when using Minoxidil is that any positive effects upon hair loss will be reserved once you stop treatment. Typically, hair loss will resume as normal after three to four months of ceasing treatment with Minoxidil. For this reason, Minoxidil should not be thought of as a hair loss cure, but as a temporary solution.

Regaine for Women Regular Strength (2%) was shown to “stabilise” hair loss in 88% of women who used it every day for 48 weeks. This means that they experienced a halt in hair loss and/or hair regrowth. If excessive water retention results in a weight gain of more than 3 pounds when a thiazide or chlortalidone is being used, diuretic therapy should be changed to furosemide, the dose of which may be increased in accordance with the patient's requirements. Diuretic dosage in children should be proportionally less in relation to weight. The renal clearance of minoxidil corresponds to the glomerular filtration rate. No substantial changes in the glomerular filtration rate and the renal plasma flow could be detected under minoxidil. Regaine has been shown to encourage hair regrowth in as little as eight weeks, however this could be up to 16 weeks for some people. You also must bear in mind that the first six weeks of using Regaine may see a temporary increase in hair loss. What happens if I miss a dose of Minoxidil? Vañó-Galván, S. et al. Safety of low-dose oral minoxidil for hair loss: A multicenter study of 1404 patients. J Am Acad Dermatol 2021; 84: 1644–1651.

We saw how the 10% strength causes more side effects. Partly, this happens because, with the increased strength, more of the minoxidil is absorbed into the bloodstream. From there it circulates to the entire body. This can cause symptoms like headaches or unwanted hair growth in other parts of the body. Minoxidil stimulates prostaglandin E 2 production by activating COX-1 [32] and prostaglandin endoperoxide synthase-1 but inhibits prostacyclin production. Additionally, expression of the prostaglandin E 2 receptor, the most upregulated target gene in the β-catenin pathway of DP cells, was enhanced by minoxidil, which may enable hair follicles to grow continuously and maintain the anagen phase. [33] The studies are very small but indicate that about one-third of patients will notice a reduction in shedding, and a third will notice improved growth in 6 months or more. This means that up to 2 in 3 people may notice benefits from oral Minoxidil. It is best to take treatment for 6 to 12 months to give it enough time to work.Sharma AN, Michelle L, Juhasz M, Muller Ramos P, Atanaskova Mesinkovska N (August 2020). "Low-dose oral minoxidil as treatment for non-scarring alopecia: a systematic review". International Journal of Dermatology. 59 (8): 1013–1019. doi: 10.1111/ijd.14933. PMID 32516434. S2CID 219561573. The recommended starting dose is 5 mg per day. If required, this dosage can later be increased up to 20 mg, and then to 40 mg daily (given as a single dose or in two divided doses). Dose increases should be made at increments of 5 mg to 10 mg minoxidil per day at intervals of three or more days. If a dose of 50 mg of minoxidil has been reached, the dose may be increased by 25 mg minoxidil per day to a maximum dose of 100 mg per day.

As with any medicine, Minoxidil comes with some mild side effects such as mild skin irritations. However if you experience any side effects you should stop using Regaine and tell your doctor or pharmacist. Minoxidil at 2% and 5% are barely absorbed systemically. However, as the strength increases, it is inevitable that at some point some of the minoxidil will be absorbed into circulation. At this point, side effects become very common and more severe. This is one of the reasons that strengths higher than 5% are not FDA-approved and are relatively difficult to find. Many medications are used outside a license in the UK, especially in Dermatological practice. While we have many patients on oral Minoxidil, your Dermatologist may not suggest this treatment to you if they do not believe your situation fulfils the criteria for them to provide you with an unlicensed medication. Topically applied minoxidil is generally well tolerated, but common side effects include itching of the eyes, general itching, irritation at the treated area, and unwanted hair growth elsewhere on the body. [19] Fukushiro-Lopes D, Hegel AD, Russo A, Senyuk V, Liotta M, Beeson GC, etal. (May 8, 2020). "Repurposing Kir6/SUR2 Channel Activator Minoxidil to Arrests Growth of Gynecologic Cancers". Frontiers in Pharmacology. 11: 577. doi: 10.3389/fphar.2020.00577. PMC 7227431. PMID 32457608.

Are there any side effects from Minoxidil?

Pericardial effusion and occasionally tamponade, has been observed in about 3% - 5% of treated patients not on dialysis. While in many cases, the pericardial effusion is associated with other potential aetiologies, there have been cases in which these potential causes of effusion were not present. Patients should be observed closely for any suggestion of a pericardial effusion and pericardiocentesis, or surgery may be required. If the effusion persists, withdrawal of minoxidil should be considered in light of other means of controlling the hypertension and the patient's clinical status. We offer a hair loss bundle with Finasteride and Regaine or a non-prescription hair loss bundle which has minoxidil, hair loss shampoo and biotin capsules. Do not use any other skin products on the same skin area on which you use minoxidil. Hair coloring, hair permanents, and hair relaxers may be used during minoxidil therapy as long as the scalp is washed just before applying the hair coloring, permanent, or relaxer. Minoxidil should not be used 24 hours before and after the hair treatment procedure. Be sure to not double your doses of minoxidil to make up for any missed doses. Kolata G (August 18, 2022). "An Old Medicine Grows New Hair for Pennies a Day, Doctors Say". The New York Times. Archived from the original on August 19, 2022.