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Understanding and Managing Side Effects of Topical Minoxidil

At Mid-County Dermatology, our St. Louis dermatologists prioritize the well-being and satisfaction of our patients, providing them with comprehensive information and effective solutions for their hair disorders. In this article, we aim to shed light on the side effects associated with topical minoxidil, a commonly used treatment for hair loss.



Man applying topical minoxidil to scalp.
Minoxidil Application St. Louis


The Safety of Topical Minoxidil

Topical minoxidil is generally regarded as a safe treatment option for various hair disorders, including androgenetic alopecia (AGA). However, it is important to note that, like any medication, there is a possibility of side effects in some individuals. By being well-informed about these potential effects and taking necessary precautions, you can maximize the benefits of minoxidil while minimizing any associated concerns.


Irritant Contact Dermatitis: A Common Side Effect

One of the most commonly reported side effects of topical minoxidil is irritant contact dermatitis. This condition manifests as itching and scaling of the skin. It is worth noting that the incidence of irritant contact dermatitis is generally lower with a 2% minoxidil solution compared to a 5% solution.


Allergic Contact Dermatitis: Identifying the Causative Agents

In some cases, individuals may develop allergic contact dermatitis as a reaction to topical minoxidil. This can be triggered by either the minoxidil itself or the propylene glycol (PG) present in the formulation. To determine the specific causative agents, a patch test should be conducted. If an allergy to PG is confirmed, alternative vehicles such as butylene glycol, glycerin, or polysorbate can be substituted. Additionally, for individuals with persistent reactions, the use of minoxidil foam (MF), a propylene glycol-free formula, should be considered. If allergy to minoxidil itself is suspected, it is recommended to discontinue the use of all minoxidil preparations.


Hypertrichosis: Unwanted Hair Growth

Hypertrichosis, characterized by excessive hair growth, is another potential side effect associated with topical minoxidil. The incidence of hypertrichosis is known to depend on the concentration of minoxidil used, with higher rates reported among individuals treated with a 5% minoxidil solution. Interestingly, hypertrichosis occurs more frequently in female patients, although the exact reasons for this gender disparity are not yet fully understood. It is important to note that excessive topical application of minoxidil does not typically lead to systemic side effects such as hypotension, abnormal heart rate, or weight gain.


If you or someone you know is concerned with hair thinning, schedule an appointment with one of our St. Louis dermatologists at Mid-County Dermatology.

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