Oral minoxidil (OM) is an increasingly common prescription treatment for androgenetic alopecia, the most frequent cause of hair loss in both men and women. The medication works systemically to stimulate hair growth, offering a convenient alternative to topical solutions. A common experience when initiating this treatment is a temporary increase in hair shedding, a phenomenon that can be alarming for individuals already concerned about hair loss. Understanding this initial shedding is important for maintaining treatment adherence, as it is an expected, temporary physiological response as the body adjusts.
How Oral Minoxidil Affects the Hair Cycle
The hair growth cycle consists of three main phases: Anagen (active growth), Catagen (transition), and Telogen (resting). Nearly 90% of hair is typically in the Anagen phase, which lasts for several years, while the Telogen phase lasts around three months before the hair sheds. Oral minoxidil acts as a hair cycle modulator, primarily by functioning as a potassium channel opener and a vasodilator. This action helps increase blood flow, oxygen, and nutrients to the hair follicles, forcing those in the resting (Telogen) phase to prematurely enter the active growth (Anagen) phase. This sudden synchronization and acceleration of the hair cycle is the direct cause of the initial shedding, as older, weaker hairs are pushed out simultaneously and replaced by new, thicker hairs.
Defining the Initial Shedding Phase
The temporary hair loss experienced when starting OM is often referred to informally as the “dread shed.” This increased hair fall is a paradoxical side effect, where the treatment initially seems to worsen the condition it is meant to resolve. Shedding is typically characterized by a diffuse increase in hair loss, noticeable as more hair accumulating on pillows, in the shower drain, or on a brush. The shed hairs are usually the miniaturized, weaker strands that were already nearing the end of their cycle. For many patients, the shedding indicates that the hair follicles are responsive to the medication, and the severity of the initial shedding may correlate with better eventual treatment efficacy. Discontinuing treatment during this phase is counterproductive, as it halts the process of replacing the old hairs with new, healthier ones.
Timeline of Shedding and Expected Regrowth
The onset of minoxidil-induced shedding typically occurs within the first few weeks of starting oral treatment, usually between 2 to 8 weeks after the first dose. For most people, the intense shedding phase is relatively short-lived, generally lasting between 4 to 12 weeks. If the shedding is severe or persists longer than six months, a consultation with the prescribing physician is warranted to rule out other potential causes. Once the shedding subsides, the regrowth phase begins, and initial visible improvements usually start around 3 to 6 months after starting treatment. Optimal results are typically seen between 6 to 12 months of consistent use, but continuous use is necessary to sustain the new growth.