Does oral minoxidil (oral form of minoxidil) cause hair shedding?

Hair Shedding with Oral Minoxidil

Yes, oral minoxidil can cause hair shedding, similar to what occurs with topical minoxidil. This initial shedding is typically a temporary effect that occurs during the early phase of treatment as hair follicles synchronize their growth cycles.

Mechanism of Action and Shedding

Oral minoxidil works through similar mechanisms as topical minoxidil, but with systemic distribution:

• It causes hyperpolarization of cell membranes as a potassium channel opener 1
• It functions as a vasodilator, increasing blood flow to hair follicles
• It pushes telogen (resting) phase hair follicles into the anagen (growth) phase 1

The shedding phenomenon occurs because:

1. Minoxidil synchronizes hair follicles, causing telogen hairs to shed earlier than they normally would
2. These shed hairs are typically replaced by new, thicker hairs in a new anagen phase 2
3. This transition creates a temporary increase in hair loss that many patients experience

Clinical Significance of Shedding

The shedding phase with oral minoxidil:

• Is generally considered a positive sign that the medication is working
• Typically occurs within the first few weeks of treatment
• Is temporary and resolves as new anagen hairs begin to grow
• Should be explained to patients before starting treatment to prevent unnecessary concern

Safety Profile of Oral Minoxidil

A large multicenter study of 1,404 patients using low-dose oral minoxidil (LDOM) found:

• No reports of life-threatening adverse effects 3
• Most common side effect was hypertrichosis (unwanted hair growth) in 15.1% of patients
• Systemic side effects were infrequent:
  • Lightheadedness (1.7%)
  • Fluid retention (1.3%)
  • Tachycardia (0.9%)
  • Headache (0.4%)
  • Periorbital edema (0.3%)
  • Insomnia (0.2%) 3

Comparative Efficacy with Topical Minoxidil

Recent research comparing oral and topical minoxidil found:

• Both formulations showed significant improvement in hair diameter after 6 months of treatment
• No significant difference in effectiveness between 1mg daily oral minoxidil and 5% topical solution
• Over 60% of patients in both groups expressed satisfaction with their treatments 4

Clinical Recommendations

When prescribing oral minoxidil:

1. Inform patients about the potential for temporary shedding during the initial weeks of treatment
2. Reassure them that this is typically a sign the medication is working
3. Advise that continued use is necessary to maintain any hair growth achieved 2
4. Consider starting with low doses (1mg daily) to minimize systemic side effects while maintaining efficacy 4
5. Monitor for common side effects, particularly hypertrichosis

Important Considerations

• Oral minoxidil may be particularly useful for patients who have difficulty with topical applications or experience scalp irritation from topical formulations 5
• The shedding phase is temporary and should not be a reason to discontinue treatment
• Regular use is required to maintain results, as hair loss will resume if treatment is discontinued 2