Side Effects of Minoxidil and Its Impact on Hair Transplant Outcomes

Minoxidil is a topical hair growth agent that was first developed as an antihypertensive agent. Prior to the management of androgenetic alopecia, it was initially used as a hypotensive agent. At present, it is used as an over-the-counter medication at a concentration of 2% to 5%. Despite the myriad advances in hair restoration medical management that have transpired over the past few decades, minoxidil remains a critical compound throughout the management of hair loss and restoration. Preoperatively, the agent is an ideal agent for hair restoration to ensure there is little shedding and assess the condition individuals hair, and both aid in closure of the donor region postoperatively and hasten the growth of newly transplanted hair after surgery. Additionally, minoxidil’s action as a hypertrichotic agent renders it quite useful for individuals having hair transplant surgery.

The mechanistic pathways by which minoxidil affects hair growth and preservation are not entirely understood. However, some of its actions can be inferred from the signaling events that follow its administration. Among its physiological responses is the dilation of blood vessels, causing increased blood flow to many tissues of the body. As androgenetic alopecia may be related, in part, to the inconspicuous diminishment of blood flow to the hair follicle, this is a likely mode of action of minoxidil. Additionally, as a potassium channel opener, minoxidil releases hyperanemic agents such as prostaglandin ex vivo. This aids in the ability of those with androgenetic alopecia by reducing androgen levels in the dermal papilla. The topical version of minoxidil is essentially well-tolerated and does not have many systemic adverse effects. The main side effects of the medication are usually related to its dermatological or ophthalmic management.

Common Side Effects of Minoxidil and Their Management

Minoxidil is one of the most common drugs used for hair restoration. The side effects of minoxidil are bothersome. In this chapter, the side effects of minoxidil will be discussed.

Minoxidil has been reported to cause minor and transient side effects. The most common effects are pruritus, dermatitis, and dry, flaky skin caused by the vehicle. Less common effects include burning of the scalp, paresthesias, and a paradoxical loss of hair. Systemic side effects are rare but include headache, dizziness, fatigue, palpitations, hypotension, edema, changes in hair color, increased hair growth on other parts of the body, hypotrichosis of the thighs, and dermatitis of the eyes or face if the drug is transferred following manual application. Nearly all patients will have minor itching and flaking, which can be controlled by the scalp care that will be discussed in the section of needling. With persistence of these symptoms, users will have the natural tendency to develop demodicosis, which will cause exacerbation of the scalp irritation. This can be managed by applying metronidazole 0.75% lotion at bedtime, and benzoylbenzoic acid 5.3%-20% (in Cetaphil Dermacontrol foam wash) head shampoo in the morning. For the benign tumor growth in women, one will have the opportunity to switch to the conventional version of the drug, which is the 5% logical for men version in the form of a foam.

The Role of Minoxidil in Improving Hair Transplant Outcomes

Minoxidil is known for its use in the treatment of alopecia. It exerts its therapeutic action by extending the anagen phase of hair and promoting quick progression of hair from telogen to anagen. It is approved for the treatment of androgenetic alopecia (AGA) since the 1980s. The efficacy of minoxidil has been proved only in controlled conditions with long-term daily application. Minoxidil can also bring benefits for subjects with hair deficiency before a hair transplantation by increasing the hair density and the anagen phase of miniaturized hair.

Hair transplantation is a surgical technique that has a good success rate in the treatment of AGA. It is based on the use of micrografts/miniaturized grafts obtained by the excision of a strip of scalp or by the excision of individual follicular units one by one. Then, the grafts are implanted in the area of alopecia. Minoxidil can improve the clinical outcome of the transplant by accelerating and enhancing the growth of the minigrafts. Moreover, minoxidil-affiliated pharmacological treatment may ensure greater hair density and adequate hair caliber of not-transplanted hair in androgenetic subjects, thus influencing the quality of the final result of the intervention. Considering the dimension of the original area of alopecia, a preoperative miniaturized hair density equal to 70 is necessary to obtain a not-noticeable density reduction. The effects on the final clinical outcome of hair transplantation can be related to the property of minoxidil that increases the anagen phase of the miniaturized hair and promotes their enlarged caliber. The improvement of the general blood irrigation is also capable of benefiting the recipient’s area of grafted hair. In conclusion, applying minoxidil during the pre- and post-operative periods of hair transplant treatment is recommended in order to obtain a better contribution to the final objective of grafting, and it can also be useful to restore AGA hair sometimes rejected by the immunoreactions related to hair transplantation.

Research Findings on Minoxidil and Hair Transplantation

Minoxidil is a widely used medication for androgenetic alopecia. The question of whether minoxidil should be stopped before hair transplantation, and if not, whether it will affect the hair transplantation results, is still debated. The author posits that stopping minoxidil before the hair transplant is not necessary, but reducing the dose to once daily before the surgery is a logical approach. Studies have shown an increased healing rate and a decreased number of effluvium in the postoperative period for patients using minoxidil after the hair restoration surgery. A study has shown that while the hair shaft diameter increased in the patients using finasteride after hair transplantation, it remained stable in the postoperative follow-up period in patients not using minoxidil.

Conclusion

Minoxidil, which is widely used in the non-surgical treatment of FPHL and male pattern hair loss, has many side effects that affect the general circulation and several systems as well. In order to avoid systemic side effects, it should be possible to advise the patients to use the least amount of medication possible and to add caution in the case of combined use with hair transplants. In hair transplant patients treated with minoxidil, an increased tendency towards postoperative edema was observed in the donor area and it was found that this side effect was more pronounced and persisted for a longer time in the patients with higher topical doses. Furthermore, the fact that medication could be metabolized in the liver and the eicosanoid of lipid metabolism and also lightly affect the effect of drugs therapeutically used for edema temporarily made temporary blindness in surgery. A significant decrease was detected in the hair density transplanted by miniature hair. The relatively small number of patients and the lack of control are limitations of this study. The results suggest that although patients think that they will benefit from postoperative use in minoxidil hair transplantation, this situation may have the potential to adversely affect the operation.