Chlorthalidone is a widely prescribed thiazide-like diuretic, or “water pill.” Its main function is to help the kidneys remove excess salt and water, which reduces blood volume and lowers blood pressure. This makes it an effective treatment for managing hypertension and reducing fluid retention (edema). Understanding the full range of possible side effects, including the potential for hair loss, is important for patients starting this long-term medication.
The Direct Answer: Chlorthalidone and Alopecia
Yes, chlorthalidone is documented as having the potential to cause hair loss, medically termed alopecia. This adverse reaction is listed in the drug’s official prescribing information and reported to regulatory bodies like the Food and Drug Administration (FDA). The causal link is recognized, suggesting the medication can trigger the condition in some users.
Hair loss from chlorthalidone is considered an uncommon or rare side effect. Most people who take this medication do not experience a noticeable change in their hair density. When it occurs, the condition is typically diffuse hair thinning across the scalp rather than localized baldness. The inclusion of alopecia in the adverse event profile confirms a direct association has been observed, even though the overall incidence rate remains low.
Understanding the Mechanism of Drug-Induced Hair Changes
The most likely explanation for chlorthalidone-associated hair loss is telogen effluvium, a disruption of the normal hair growth cycle. Medications can prematurely push a significant number of active hair follicles from the growing phase (anagen) into the resting phase (telogen).
Once follicles enter this premature resting state, they remain dormant for approximately two to four months before being shed. This explains why hair loss often becomes noticeable months after a person starts the medication. The diuretic action of chlorthalidone may also interfere with the complex cellular process of hair growth by altering the body’s balance of essential minerals and electrolytes.
Chlorthalidone increases sodium excretion, but this process can also lead to the loss of vital micronutrients, including potassium and magnesium. These minerals are necessary cofactors for the rapid cell division required for healthy hair follicle function. Depletion of these elements stresses the hair matrix cells, compromising their ability to sustain the growth cycle.
Frequency and Management of the Side Effect
Data on the precise frequency of chlorthalidone-induced hair loss is primarily gathered through post-marketing surveillance, a system relying on voluntary reports from healthcare providers and patients. This reporting suggests that alopecia is a rare occurrence, meaning the incidence rate is likely less than one percent of users. Because reporting is not mandatory, the exact number is difficult to determine, but the effect is clearly not widespread.
For patients who suspect their hair loss is linked to the medication, the appropriate first step is to contact their prescribing physician. It is not recommended to stop the medication abruptly without medical guidance, especially when treating hypertension, which requires continuous management. The physician will evaluate the timeline of the hair loss and may order blood tests to check for other potential causes, such as thyroid issues or significant mineral deficiencies.
If chlorthalidone is identified as the likely cause, management typically involves a discussion of the risk-versus-benefit profile. Possible solutions include adjusting the dose to the lowest effective level or switching to an alternative class of antihypertensive medication. Drug-induced telogen effluvium is usually reversible, and hair growth commonly begins to resume within three to six months after the causative drug is stopped. Full cosmetic recovery can take 12 to 18 months.