Zinc Supplements For Hair Loss: A Hard Look Into The Science

Article Summary

Zinc is a popular trace element found in hair growth supplements. Animal studies suggest that zinc is required for healthy hair cycling. Human studies suggest that zinc deficiencies can cause hair loss from telogen effluvium. One study found that zinc sulfate might help with non-descript hair loss in women, though not nearly as much as 2% minoxidil. In this article, we dive into the science behind zinc, its connection to hair loss & hair growth, and whether zinc supplements are worth their costs in hair recovery.

Full Article

Zinc is an essential nutrient found in a variety of foods. It is an essential trace element, meaning that the body cannot generate it on its own and that it is usually only present in very small quantities. An adult human contains around 2-3 g of zinc, about 0.1% of which is replenished daily.^[1]Maret, W., Sanstead, H.H. (2006). Zinc requirements and risks and benefits of zinc supplementation. Journal of Trace Elements in Medicine and Biology. 20(1). 3-18. Available at: … Continue reading Zinc is included in many supplements, including those marketed towards hair growth.

In this article, we will be taking a deep dive into the science behind zinc and whether supplementation with zinc may be beneficial for different types of hair loss.

Key Takeaways

• What is it? Zinc is an essential element that is involved in many processes within the body. There is some evidence to suggest that zinc may improve hair loss conditions; however, the studies available are either small or do not collect objective measurements. A study completed in mice suggested that zinc supplementation has effects on hair follicle cycling (slows the onset of the growing stage and elongates the transition stage). After treating mice with a chemotherapy drug cyclophosphamide short-term treatment with zinc was found to enhance the recovery of hair growth, but long-term treatments actually slowed hair recovery (more detail below). 
• Evidence Quality:  The evidence quality is 51/100 based on our metrics.
• Clinical Data: 
  • Two studies looking at the effects of zinc supplementation on alopecia areata showed some improvement in hair loss. However, the photos were not definitive, and the researchers took subjective measurements (such as visually grading the hair loss) instead of objective, numerical measurements (like a trichogram).
  • A case study involving a woman with hypothyroidism, zinc deficiency, and profound diffuse alopecia was administered a 140 mcg capsule of zinc twice daily (alongside other multivitamins) for 4 months. After 4 months of treatment, a notable increase in hair regrowth was seen.^[2]Betsky, A., Sarita, S.B. (2013). Zinc deficiency associated with hypothyroidism: an overlooked cause of severe alopecia. International Journal of Trichology. 5(1). Available at: … Continue reading However, because the patient was also given other multivitamins, it is not possible to know if the positive effects were from zinc alone. Moreover, it is impossible to deduce general trends from an isolated case study.
  • A study compared the effects of zinc, calcium pantothenate, a combination of zinc and calcium pantothenate, and minoxidil in 73 women aged between 15-75. Zinc and calcium (alone or together) did result in a modest increase in hair follicle growth compared to the baseline levels. The positive effects did not reach a similar level to that achieved with minoxidil, however.^[3]Siavash, M., Tavakoli, F., Mokhtari, F. (2017). Comparing the Effects of Zinc Sulfate, Calcium Pantothenate, Their Combination and Minoxidil Solution Regimens on Controlling Hair Loss in Women: A … Continue reading
• Safety: The recommended zinc treatment varies depending on the person’s life stage (Figure 9). However, if the person does not have a zinc deficiency, treatment may lead to side effects, including nausea, dizziness, headaches, upset stomach, vomiting, and loss of appetite.
• Who Might Benefit From Zinc:  There is some evidence to suggest that zinc supplementation might benefit those with alopecia areata, but the researchers did not use quantitative measurements of hair loss (like trichogram). Furthermore, a case study has found that zinc may benefit patients with hypothyroidism and zinc deficiency-related diffuse alopecia.

Zinc is an essential micronutrient that plays an important role in enzymatic processes within the body, as well as being involved in protein and nucleic acid synthesis, and it is involved in various metabolic pathways and cell functions.^[4]Kil, M.S., Kim, C.W., Kim, S.S. (2013). Analysis of serum zinc and copper concentrations in hair loss. Annals of Dermatology. 25(4). 405-409. Available at: https://doi.org/10.5021/ad.2013.25.4.405

Is there evidence for an effect of zinc on hair follicles?

What scientific evidence is there to show that zinc can actually affect hair follicle biology in a way that could help treat hair loss?

In one study, 6-8 week-old female mice were treated with high doses of oral zinc in their daily water supply for differing lengths of time (over a total of 27 days). Zinc was given alone or in combination with the chemotherapeutic drug, cyclophosphamide to determine the potential protective effects of zinc on chemotherapy-induced hair loss.^[5]Plonka, P.M., Handjiski, B., Popik, M., Michalczyk, D., Paus, R. (2005). Zinc as an ambivalent but potent modulator of murine hair growth in vivo- preliminary observations. Experimental Dermatology. … Continue reading By 8 weeks old, the back skins of the mice were naturally in the non-growing (telogen) phase. Hair follicles were then induced into the growing phase (anagen) by depilatory waxing (removal of hair shafts). Usually, this is achieved by applying a mixture of paraffin wax and resin to the dorsal skin.

Mice treated with zinc took longer to enter anagen than the control mice (Figure 1a). Furthermore, the zinc-treated mice took longer to enter the transitional phase (catagen) than control follicles; however, once in catagen, the mice spent longer in that stage than control-treated mice (Figure 1b). 

When determining the effects of zinc on chemotherapy-induced alopecia (CIA), zinc treatment was found to slow the onset by one day, but it did not prevent CIA (Figure 2a). For mice treated with zinc and cyclophosphamide together (Figures 2b & c), there was no difference in the number of anagen hairs (both decreased), but the number of hairs in the transition stage (catagen) was decreased for the mice treated with zinc and cyclophosphamide compared to cyclophosphamide alone. 

So, short-term zinc treatment may help with the rescue of hair growth following chemotherapy-induced alopecia, but long-term treatment may actually be detrimental to hair growth. However, zinc doesn’t appear to have any capacity to prevent chemotherapy-induced alopecia, although it may possibly delay its progression to a modest extent.

Of course, this information is all from mouse experiments, so let’s examine the effects that zinc supplementation might have on the treatment of different hair loss disorders in humans.

Clinical Data

The therapeutic effects of oral zinc supplementation to treat hair loss have been assessed in multiple clinical studies with varying results.

One study, completed in 67 patients (41 males and 26 females) aged between 1.6 – 68, focussed on patients with patchy alopecia areata who had not used any hair loss treatments for 6 months. Patients were recruited into a randomized, placebo-controlled, double-blind cross-over trial between February 2008 and September 2009.^[8]Sharquie, K.E., Noaimi, A.A., Shwail, E.R. (2012). Oral Zinc Sulphate in Treatment of Alopecia Areata (Double Blind; Cross-Over Study). Journal of Clinical & Experimental Dermatology Research. … Continue reading Hair loss was graded “clinically” (although the researchers mention nothing about the person doing the examination) once a month based on the level of hair loss:

Grade 0 – no hair regrowth

Grade 1 – partial hair regrowth with vellus hairs (fine, thin, short hairs)

Grade 2 – complete hair regrowth with terminal hairs (course, pigmented, and long hairs)

Participants were randomly allocated to receive either 5 mg/kg/day of zinc sulfate (Group A – 37 patients) or placebo capsules (Group B – 30 patients). After 3 months the treated group switched to the placebo, and the placebo switched to the treated group. After 3 months, 22 out of 37 participants in group A showed grade 2 regrowth, increasing to 23 people at the 6-month point (3 months after stopping the treatment) (Figure 3). In group B, 3 participants showed grade 2 regrowth, increasing to 20 after 6 months.

The researchers also showed a before-and-after photo of a patient treated with zinc sulfate. However, in our opinion, there does not appear to be any real effect on hair regrowth and density (Figure 4); in fact, it looks like the exact same photo. This is a huge red flag that brings into doubt the veracity of the whole paper—because of this, the results should be taken with a huge pinch of salt.

Another study was completed on 15 patients diagnosed with alopecia areata and who also had low zinc levels (10 male and 5 female). Patients were supplemented with zinc for 12 weeks.^[11]Park, H., Kim, C.W., Kim, S.S., Park, C.W. (2009). The therapeutic effect and the changed serum zinc level after zinc supplementation in alopecia areata patients who had a low serum zinc level. … Continue reading 

After zinc supplementation, 7 patients showed a “marked recovery” (defined as cosmetic satisfaction or terminal hair regrowth of more than 60% on the hair loss patch), 2 patients showed a “partial recovery” (defined as terminal hair regrowth of less than 60% on the hair loss patch), 2 patients showed a ”poor recovery” (only vellus hair regrowth on the hair loss patch), and 4 patients showed “no recovery” (aggravation or an unchanged alopecia areata state as compared to before therapy) (Figure 5). 

Serum zinc levels were found to be significantly increased in those with a positive response – i.e., those that showed either a marked recovery or partial recovery – compared to the baseline measurements. However, the patients who showed a negative response did not show a significant increase in serum zinc levels (Figure 6).

Zinc supplementation has also proved to be beneficial in patients with zinc deficiency and diffuse alopecia related to hypothyroidism (low thyroid activity). Zinc and other trace elements are required for the synthesis of thyroid hormones, and deficiency of these can result in hypothyroidism.^[14]Betsky, A., Sarita, S.B. (2013). Zinc deficiency associated with hypothyroidism: an overlooked cause of severe alopecia. International Journal of Trichology. 5(1). Available at: … Continue reading Plus, there is growing body of research linking hypothyroidism to hair loss.^[15]Popa. A., Carsote, M., Cretoiu, D., Dumitrascu, M.C., Nistor, C.E., Sandru, F. (2023). Study of the Thyroid Profile of Patients with Alopecia. Journal of Clinical Medicine. 12(3). 1115. Available at … Continue reading

For example, a case study involving a 28-year-old woman with hypothyroidism, zinc deficiency, and profound diffuse alopecia was treated with zinc supplementation. The alopecia was characterized as diffuse with scaly lesions on the neck (Figure 7).^[16]Betsky, A., Sarita, S.B. (2013). Zinc deficiency associated with hypothyroidism: an overlooked cause of severe alopecia. International Journal of Trichology. 5(1). Available at: … Continue reading 

The patient showed lower than normal thyroid levels (T3 70 ng/dl – normal is 80-200, T4 2 mcg/dl – normal is 4-12, and thyroid stimulating hormone was 64 IU/ml – normal is 0.0-4.5) and was treated with thyroid supplements however there was no detectable improvement in hair loss. As the patient also showed lower-than-average zinc serum levels a 140 mcg capsule was given twice a day, alongside other multivitamins. After one month, the skin lesions had cleared up; after 4 months, zinc supplementation showed notable regrowth of hair (Figure 7).

One of the key issues with the above studies is the lack of objective data collection when measuring the levels of hair loss and the amount of hair regrowth. When measuring hair loss and hair regrowth subjectively, researchers leave themselves open to bias. Moreover, alopecia can spontaneously resolve, which is why it is hard to deduce any clear effect from a case study.

One further study, however, did use objective data measurements to measure the effects of zinc on hair regrowth on a larger number of people. One 4-month study used zinc and calcium pantothenate alone and in combination with each other and then compared their effects to 2% minoxidil treatment in 73 women aged between 15-45 with hair loss (Although they do not specify what type).^[18]Siavash, M., Tavakoli, F., Mokhtari, F. (2017). Comparing the Effects of Zinc Sulfate, Calcium Pantothenate, Their Combination and Minoxidil Solution Regimens on Controlling Hair Loss in Women: A … Continue reading 

Participants were randomized into either a 50 mg zinc-treated group (1 tablet once daily), a 100 mg calcium pantothenate-treated group (1 tablet once daily), a combination-treated group (1 tablet twice weekly), and a 2% minoxidil group (1 ml applied topically twice daily). Hair density and thickness were measured using a dermascope – a handheld visual-aid similar to a magnifying glass, used for close examination of the skin and hair. The change in hair density and hair thickness are shown below (Figure 8).

While each treatment appeared to lead to a positive change in hair density and thickness, minoxidil treatment led to the highest increase in hair density. Moreover, because there was no raw data provided, it is not possible to know if the effects on each group were due to a few participants who may have responded better than anyone else. It is also unclear whether any of the differences are statistically significant. The researchers should have also included a placebo control group.

Overall, while there may be some individual case studies that suggest some may benefit from zinc supplementation, it is very difficult to discern whether zinc would be beneficial more widely.

Is Zinc Supplementation Safe?

The recommended daily intake of zinc varies depending on age (Figure 9). Importantly, too much zinc can be harmful, with symptoms including nausea, dizziness, headaches, upset stomach, vomiting, and loss of appetite.^[20]NIH, (no date) Zinc Fact Sheet for Consumers. Available at: https://ods.od.nih.gov/factsheets/Zinc-Consumer/ (Accessed: 27 April 2023)

Who might benefit from Zinc Supplementation?

While there is some evidence that zinc supplementation may benefit those with alopecia areata, most studies did not use objective measurements of hair loss (such as phototrichograms). Furthermore, studies that did use objective data collection did not state the types of hair loss participants had, and the zinc treatments did not perform as well as other drug treatments like minoxidil.

Zinc supplementation may be appropriate for patients with hypothyroidism and zinc deficiency-related diffuse alopecia; however, large-scale studies should be conducted to confirm this. There is no indication that zinc would generally be useful across different types of hair loss.