Human chorionic gonadotropin (HCG) is a naturally occurring glycoprotein hormone. Its potential connection to hair loss has become a growing public concern, largely fueled by its use outside of traditional medicine. While hormonal changes influence the hair cycle, the relationship between HCG administration and hair thinning is complex and often misunderstood. Addressing this requires understanding what the hormone is and the context in which it is typically used.
Understanding Human Chorionic Gonadotropin
HCG is a hormone produced primarily by the placenta during pregnancy, and its presence is what home pregnancy tests detect. Its main biological function is to support the corpus luteum, ensuring the continued production of progesterone to sustain early gestation. The hormone is composed of two subunits, with its alpha subunit similar to other pituitary hormones like luteinizing hormone (LH) and thyroid-stimulating hormone (TSH).
In medical practice, HCG is an FDA-approved prescription drug used to treat specific conditions, such as female infertility and other hormone imbalances. However, HCG has also been controversially promoted as a weight-loss aid, typically as part of the “HCG diet.” This protocol pairs HCG injections or drops with a severely restrictive diet, often limiting intake to 500 calories per day. The FDA does not approve HCG for weight loss, and scientific evidence does not support its effectiveness.
The Direct Hormonal Connection to Hair Loss
The idea that HCG could directly cause hair loss stems from its role influencing other endocrine pathways. HCG binds to the luteinizing hormone/chorionic gonadotropin receptor (LHCGR), which stimulates the production of steroid hormones, including androgens like testosterone. An increase in androgens, or their potent derivative dihydrotestosterone (DHT), is a well-established factor in genetic hair loss, known as androgenic alopecia.
The link between therapeutic HCG use and hair loss is generally considered complex and indirect. Case reports suggest that combining HCG with other hormone therapies, like testosterone, may precipitate androgenic alopecia in genetically susceptible individuals. Furthermore, the rapid hormonal shifts experienced while taking HCG may push hair follicles from the active growth phase (anagen) into the resting phase (telogen). However, this hormonal mechanism is often overshadowed by other factors present in its non-medical use.
Dietary Stress and Telogen Effluvium
The most common cause of hair thinning observed during or shortly after the HCG diet is not the hormone itself, but the severe caloric restriction it mandates. A very low-calorie diet (VLCD), defined as 800 calories or less per day, places significant physical stress on the body. This shock can trigger Telogen Effluvium (TE), which is a temporary form of diffuse hair shedding.
Hair loss from TE typically begins two to three months after the initiating stressful event, such as rapid weight loss or severe dietary change. Hair follicles are metabolically active cells, making them sensitive to a sudden lack of energy and nutrients. These restrictive diets often result in deficiencies of protein, iron, zinc, and B vitamins, all necessary for healthy hair growth. When the body is starved of these building blocks, it prioritizes resources for essential functions, diverting them away from non-essential processes like hair production.
Addressing and Reversing Hair Thinning
Hair loss caused by Telogen Effluvium is typically reversible once the underlying stressor is removed and nutritional balance is restored. The hair shedding phase generally slows down and stops within three to six months after discontinuing the restrictive diet and adopting a balanced eating pattern. New hair growth usually begins a few months later, and a return to normal hair density can take six to twelve months.
Recovery is accelerated by ensuring adequate protein consumption and addressing specific micronutrient deficiencies through a nutrient-dense diet. Correcting low levels of iron, zinc, and B vitamins is important, and supplementation may be necessary if blood work confirms a deficiency. If shedding is severe, prolonged beyond six months, or accompanied by other concerning symptoms, consulting a dermatologist is recommended to rule out other causes and establish a personalized recovery plan.