Minoxidil Side Effects
When Dr Bonaros prescribes minoxidil as part of your hair restoration journey, your safety is as important as the hair regrowth results. While the medication is well-tolerated in both men and women, there are minoxidil side effects to be aware of.
Read on to familiarise yourself with the potential adverse effects of minoxidil, as advised by the office of Dr Bonaros. An award-winning hair restoration healthcare professional.
Reviewed by Dr Epameinondas Bonaros
Table of Contents
Overview of Minoxidil
The FDA approved topical minoxidil for androgenetic alopecia (pattern hair loss) in 1988. While oral minoxidil is still prescribed off-label for hair loss in the 21st century, it is used widely in hair restoration protocols.
Minoxidil — A Hair Loss Breakthrough
Upjohn, a pharmaceutical company now part of Pfizer, did not set out to create a breakthrough in hair loss treatments with minoxidil. Neither intended to develop a medication for high blood pressure, which is how the company first introduced minoxidil to the market.
During the 1950s, Upjohn experimented with a compound to find a treatment for stomach ulcers. While their researchers failed to make headway on ulcers, they developed a medicine that relaxed blood vessels. The effect was improved blood flow, which in turn lowered blood pressure.
Minoxidil, approved by the US Food and Drug Administration (FDA) in 1971, proved highly effective in treating high blood pressure (hypertension).
As a result, its use became more widespread. Doctors frequently placed hypertensive patients on protocols that extended beyond the recommended duration. Soon, a new side effect emerged — hypertrichosis. Hypertrichosis is the clinical term for excessive unwanted hair growth on the body.
During this period, treating hair loss needed a rehaul, and word spread of the blood pressure medicine’s side effects. Notably, minoxidil taken orally caused hypertrichosis in 60-80% of patients taking it for blood pressure.
While Upjohn initially deemed the unexpected hair growth a trivial side effect of oral minoxidil, it was ultimately recognised as an unintended benefit for hair restoration.
Interesting note: Returning to the unexpected origins of minoxidil as a hair restoration medication, excessive hair growth caused by its use has been turned to the benefit of men seeking to grow beards and chest hair.
Mechanism of Action
Despite extensive research on the medication, minoxidil’s exact mechanism of action on male and female pattern hair loss is still largely unknown. It is known to promote blood flow around hair follicles in the scalp. This helps stop the miniaturisation and pushes the follicles into a new hair growth phase.
Available Forms
The topical minoxidil product line has expanded from liquid solutions to foam and shampoo that can be gently massaged on the scalp. However, it is essential to apply topical minoxidil carefully, as the solution can stain clothing or fabrics.
Oral medications are available in low and high doses for systemic administration. Many healthcare professionals prefer oral minoxidil due to its efficacy and patient compliance.
The topical minoxidil solution is available over the counter in the UK, while you would need a prescription to use oral capsules for hair loss off-label.
Side Effects of Minoxidil
Unfortunately, not all unexpected symptoms, such as the development of minoxidil for hair loss, are positive. However, with awareness, adverse effects can be managed to make the most of your treatment. Be sure to read the patient information leaflet for detailed instructions and precautions.
These are noted as minoxidil hair loss treatment side effects of the oral and topical formulations.
More Common Minoxidil Side Effects
Hypertrichosis, the side effect that first drew attention to minoxidil’s potential as a hair regrowth treatment, is still prominent even with improved formulations. The extent of hair growth depends on the strength of the formulation.
Other more common secondary reactions include:
Hair shedding: Temporary shedding, nicknamed “dread shed,” can be expected during the first six weeks of the treatment. It is so common because minoxidil transitions hair follicles into the anagen phase. This temporary effect typically stops within four weeks.
Fluid retention: Sometimes seen in patients taking higher doses of oral minoxidil, fluid retention can cause ankle swelling or puffy lower legs. Adverse changes in body weight can also occur.
Low blood pressure: Minoxidil is used in significantly higher doses to treat hypertension than for hair loss. Yet low-dose minoxidil can also lower blood pressure, leading to lightheadedness and dizziness.
Uncommon Side Effects
In sporadic cases, men and women have experienced the following symptoms:
-
Breast tenderness
-
Chest pain
3. Heart failure
4. Insomnia
5. Nausea
6. Nightmares
7. Pericarditis
8. Skin rash
9. Vomiting
10. Weight gain
Topical Minoxidil Side Effects
Often, minoxidil topical solution side effects can be attributed to an allergy to the medication or sensitivity to propylene glycol or alcohol.
A common but temporary side effect of propylene glycol is contact dermatitis, which causes dryness, skin irritation and redness. Your healthcare provider should perform a patch test to assess your sensitivity to topical minoxidil.
In a cross-sectional study of 453 patients using a minoxidil solution, study leaders hypothesised that prolonged use causes hair discolouration. This effect was particularly noted among individuals with a family history of grey hair.
Most patients were of Saudi Arabian descent, with the majority between 18 and 34. 26% of patients reported greying. Additionally, 14.8% experienced other shades, including light brown, orange and yellow.
Oral Minoxidil Side Effects
The incidence of headaches due to low-dose oral minoxidil (LDOM) varies widely across studies.
A multicenter study on the safety of LDOM, with 1404 men and women, recorded only 0.4% experiencing headaches. A smaller randomised trial, with 49 male patients, recorded a significantly higher incidence of 14%.
Minoxidil Side Effects in Men
Erectile dysfunction and other sexual side effects in men are not uncommon in hair loss medications like dutasteride and finasteride. In contrast, minoxidil does not work on a hormonal level, so it has extremely limited to no reported sexual side effects.
Even a 2016 analysis of clinical reports submitted over 10 years to the FDA Adverse Event Reporting System (FAERS), which showed higher figures than other reports, supports this. Less than 5% of patients reported erectile dysfunction.
Minoxidil Side Effects in Women
Though not a woman-specific side effect, hypertrichosis is often more pronounced in female patients, particularly with 5% topical minoxidil. The reason for this disparity in unwanted hair growth between genders is unclear. Some female patients may have hair follicles that are more responsive to minoxidil.
Taking minoxidil during pregnancy or breastfeeding is not advised for the potential risks. While studies on humans are limited, animal studies have shown adverse reactions on the foetus.
Foetal minoxidil syndrome describes a set of symptoms that can occur in a foetus or newborn as a result of maternal minoxidil use during pregnancy. It is infrequent, and there have been no conclusive studies on the conditions.
These symptoms include:
- Hypertrichosis gradually diminishes within several months postpartum.
- Cardiac anomalies
- Neurodevelopmental issues
- Other malformations: Gastrointestinal, renal, and limb abnormalities have been reported.
In a 2016 review of differences in reproductive toxicology between alopecia medicine, an extremely small percentage of women reported irregular periods while taking minoxidil. There were notably no reports of sexual side effects.
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FAQs on the Side Effects of Minoxidil
At the Dr Bonaros Clinic, we cultivate a safe environment for honest questions about interventions for hair disorders.
Read further for our answers to common queries about topical and oral minoxidil.
How common are minoxidil’s side effects?
Minoxidil side effects are uncommon among most users and tend to present minimal effects. Research on patients taking minoxidil shows that most individuals experience only mild reactions, if any.
Before starting treatment, you should always discuss any preexisting conditions with your healthcare professional. This can help minimise the risk of unwanted secondary effects and ensure the treatment is safe for you.
For instance, though studies are lacking, individuals with high blood pressure or heart conditions should not use topical solutions. If too much is absorbed, the severity of these conditions can be exacerbated.
Do lifestyle changes help with minoxidil side effects?
Yes, making overall lifestyle changes can reduce or altogether avoid the side effects of minoxidil.
- Cutting out substances like coffee and alcohol can make a big difference to your health. Alcohol contributes to high blood pressure, and caffeine could contribute to a fast heart rate, which leads to palpitations.
- Many patients do not achieve the best results from their minoxidil regimen due to poor compliance. Establishing a strict routine is essential. Failing to adhere to the correct dosage can result in severe unintended effects.
- It’s best to quit smoking on any hair restoration journey, as tobacco and nicotine are linked to hair loss.
In a case study published in the 1990s, two patients developed an interesting side effect from 2% topical minoxidil — a smoking intolerance. This intolerance, however, has not been studied further.
Can I leave minoxidil on overnight?
Yes, it is safe to leave the minoxidil solution on your skin overnight. However, it’s vital to ensure the solution is fully dry before bed to avoid transferring it onto your pillow and then to your face.
Typically, topical minoxidil is applied twice daily, lasting about 12 hours between applications. Always follow the manufacturer’s instructions and your prescribing doctor’s advice to use the treatment effectively.
What should I do about a missed dose of minoxidil?
Patient compliance is vital to getting the best results from minoxidil, but oversights happen. If you miss a dose, two variables should be considered.
- You can still take or apply minoxidil if not too much time has passed.
- Suppose it is too close to your next dose; skipping the missed dose and resuming your regular schedule is best. Never double your dose, as it could trigger overdose side effects.
Overdosing on topical or oral minoxidil can cause side effects such as:
- Refractory circulatory shock
- Trouble breathing
- Acute pulmonary oedema
- Fluid retention
- Tachycardia-induced acute heart failure
- Subendocardial ischemia
- Seizures
- Fainting
Can I take oral finasteride and minoxidil together?
Minoxidil and other medications, such as oral finasteride, can be prescribed together to stimulate hair growth. These medications target hair follicles in different ways.
Besides topical and oral minoxidil, what other medications are available for hair loss?
While topical minoxidil was among the first approved medicines to treat hair loss, other medications have since also proven effective.
Here are two other medications that we prescribe at our clinic:
Dutasteride: When used off-label, dutasteride is among the most effective treatments for male pattern baldness. Dutasteride for women has shown promising results, but it holds severe side effects during pregnancy and carries a breast cancer risk.
Finasteride: Topical and oral finasteride are approved in the UK to treat pattern hair loss and are effective in men over 18. However, extreme caution is advised when prescribing finasteride to women as it can cause congenital disabilities during pregnancy.
What are the symptoms of a minoxidil allergy?
Minoxidil can cause severe allergic reactions in some patients. Thailand researchers conducted a systematic review and meta-analysis of 43 studies examining the primary allergens in allergic contact dermatitis caused by topical minoxidil use.
Minoxidil was found to be the main allergen in 74.7% of patients, with propylene glycol being the second most common at 17.1%. Other allergens identified included canrenone, latanoprost, estradiol, butylene glycol, and methylchloroisothiazolinone/methylisothiazolinone.
Common symptoms of allergic contact dermatitis from topical minoxidil:
- Pruritus (skin irritation)
- Scaling scalp
- Redness
Other allergic symptoms from minoxidil could include:
- Difficulty breathing
- Swelling of the throat or tongue
- Hives
Contact our clinic at info@drbonaros.com or 0141 340 9098 to
find out more about getting on a topical or low-dose oral minoxidil treatment protocol.
Dr Bonaros: Award-Winning UK Hair Loss Expert
Your path toward restored confidence deserves personalised attention. Here at the Dr Bonaros hair loss clinic in Glasgow, our team takes time during each consultation to truly understand what brings you through our doors, whether this is early signs of change or more established hair concerns.
Dr Bonaros is a British Association of Hair Restoration Surgery (BAHRS) member and Scotland’s sole member of the International Society of Hair Restoration Surgery (ISHRS).
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