Side effects minoxidil
Side effects minoxidil

WHAT IS MINOXIDIL AND HOW DOES IT HELP HAIR GROWTH?

Minoxidil is a vasodilator that works by widening blood vessels and opening potassium channels. Vasodilators prevent hair loss by providing the hair follicles with more fuel it enables the follicle to grow thicker hair. This thickening action will only apply to new hair that grows in, not to the existing fine hair. Minoxidil is a prodrug; a prodrug is altered within the biological system, in this case, the scalp.

Minoxidil is converted by sulphation, via the sulphotransferase enzyme, into its active form: minoxidil sulphate. Suitable levels of minoxidil must be converted into minoxidil sulphate to work. The level of sulphotransferase enzyme in the scalp will determine how responsive you are to the treatment by minoxidil [3].

HOW SAFE IS MINOXIDIL?

Minoxidil is FDA approved to treat male and female pattern hair loss at concentrations of 2% and 5%.  Minoxidil is usually applied to thinning areas of the scalp and takes around 12 months to achieve maximum result.  It’s efficacy rate stand at around 40% when used as a stand alone treatment and clinical response is usually seen after 3-6 months.

Clinical trials show a 5% topical solution is superior to 2% minoxidil after 48 weeks of therapy, though side effects were more common in the 5% minoxidil group.  Efficacy was evaluated by variables such as vellus to terminal hair transition at week 48 and change in hair growth and scalp coverage.

When deciding whether to use minoxidil as part of a treatment programme the side effects must be taken in to consideration. Whilst minoxidil is generally well tolerated at 2%, trials show an increase occurrence or pruritus, irritation at application site and hypertrichosis in female patients [2].

WHAT ARE THE SIDE EFFECTS OF MINOXIDIL?

  1. Allergic reaction – There have been some reports of allergic reaction to propylene glycol, a non active ingredient added to minoxidil to increase absorption.  Around 4% of the population is estimated to be sensitive to propylene glycol.  A 5% minoxidil solution contains around 50% propylene glycol and the 2% minoxidil contains around 30%.  Patients that exhibit allergic reactions to minoxidil are not candidates for topically applied minoxidil.  Patch tests should always be carried out before using minoxidil, though patch test results do not ensure minoxidil will continue to be tolerated.  Allergic reaction is less common with foam formulation as it does not contain propylene glycol.
  2. Contact dermatitis – Contact dermatitis has been observed to occur frequently in patients treated with topical minoxidil over a long period of time (18 months +).  Patch testing results show that minoxidil is a frequent scalp sensitiser amongst hair loss patients.  Contact dermatitis can lead to acute telogen effluvium if minoxidil treatment is not stopped.  If contact dermatitis occurs when using a 5% solution, then it is recommended to switch to a 2% solution.  If dermatitis persists, it is advisable to stop minoxidil therapy.
  3. Pruritus + scaling – This is the most common side effect of minoxidil, this is a reaction to the propylene glycol or the minoxidil itself.
  4. Hypertrichosis – Another common side effect that is often reported to be close to the area of application.  This is mainly an issue for female patients.  In cases of hypertrichosis it is advisable to use a 2% solution and to apply minoxidil at least 1.5 inches from the hairline.
  5. Increased hair loss – In some cases, there may be a temporary increase in shedding at the start of the treatment.

REDUCING THE RISK OF SIDE EFFECTS WITH MINOXIDIL

Some reactions to minoxidil are unavoidable, it is advisable to carry out a 24 hour patch test.  If you experience no adverse reactions are 48 hours you can assume it is safe to use minoxidil but be aware an intolerance to minoxidil or the solvents within the solution can develop over time.  Avoid using products that contain alcohol in the same area you apply minoxidil unless this is approved by a healthcare provider.

Whilst you can safely use relaxers, hair dyes and perms, it is recommended to not apply these to the scalp on the same day as using minoxidil.  If you do need to use any chemical treatment on your hair, skip minoxidil for the day of the treatment and for 24 hours after application of any chemicals to the scalp.  For the vast majority, minoxidil is able to restore hair growth safely, but there are potential risks.  Most individuals experience very minor adverse risks, such as itching or mild stinging, due to the vasodilative effect of the therapy.

WHAT ARE THE SIDE EFFECTS AFTER I STOP USING MINOXIDIL?

Minoxidil is an FDA approved topical solution that supports the regrowth of hair.  Originally marketed for the treatment of high blood pressure, it was found to prevent the development of androgenic alopecia [1].  Minoxidil is usually used for a receding hair line and is usually applied directly to that area.  Whilst minoxidil is normally a safe and effective topical treatment.  Cessation of minoxidil therapy will mean new hair growth is likely to be lost and hair loss may progress further.

YOU’VE GOT YOUR HAIR BACK! NOW WHAT??!

Using minoxidil as a stand-alone treatment will not leave you with long-term, lasting hair regrowth.  Topical application of minoxidil can cause mild side effects like dryness or irritation of the scalp so it may not be feasible to continue to use minoxidil for an extended period of time.  To avoid reversal of ‘hair gains’ brought about by minoxidil, it is imperative nutritional therapy takes place alongside minoxidil therapy.

WHAT CAN BE EXPECTED AFTER CESSATION OF MINOXIDIL TREATMENT?

If minoxidil therapy is conducted alongside nutritional therapy for a period of 12 -24 months it is likely that hair regrowth will be retained for the longer term.  Speak to a hair specialist and check for vitamin and mineral deficiencies to guard against future hair loss incidence.

3 WAYS TO INCREASE THE EFFECTIVENESS OF MINOXIDIL

  1. Get the dosage right – Apply once a day for a minimum of 6 months.  Applying minoxidil daily will support adequate blood flow throughout the day and night (approximately 22 hours of action).
  2. Massage to stimulate the scalp – Massaging the scalp for 3 minutes will increase the activity of minoxidil.
  3. Correct essential nutrients –  Adequate levels of B12, iron, sulphur, and zinc are required to support the actions of minoxidil [4].

THE FINAL WORD

Minoxidil has been used in the treatment of androgenic alopecia since the early 1980’s, leading to the realisation that hair loss is a treatable  condition.

Some trials have shown minoxidil to be effective, however, there are some inconsistencies that have been reported.  The inconsistencies have been largely attributed to the samples in the trial. Controls accounting for blood haemoglobin, and mineral status (ferritin and zinc) would offer more reproducible results.  Females seeking to commence hair loss treatment with minoxidil should evaluate vitamin and mineral status with a medical professional or hair loss specialist for greater results than treating hair loss with just minoxidil alone.

REFERENCES

  1. Vanderveen EE, Ellis CN, Kang S, Case P, Headington JT, Voorhees JJ, Swanson NA. Topical minoxidil for hair regrowth. Journal of the American Academy of Dermatology. 1984 Sep 1;11(3):416-21.
  2. Lucky, A.W., Piacquadio, D.J., Ditre, C.M., Dunlap, F., Kantor, I., Pandya, A.G., Savin, R.C. and Tharp, M.D., 2004. A randomized, placebo-controlled trial of 5% and 2% topical minoxidil solutions in the treatment of female pattern hair loss. Journal of the American Academy of Dermatology, 50(4), pp.541-553.
  3. SDeVillez RL, Jacobs JP, Szpunar CA, Warner ML. Androgenetic alopecia in the female: treatment with 2% topical minoxidil solution. Archives of dermatology. 1994 Mar 1;130(3):303-7.
  4. Tanaka Y, Aso T, Ono J. Combination Therapy to Treat Asian Female Pattern Hair Loss. Journal of Cosmetics, Dermatological Sciences and Applications. 2019 Aug 20;9(3):216-22.

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