Lisinopril is a widely prescribed Angiotensin-Converting Enzyme (ACE) inhibitor. It is a first-line treatment for managing high blood pressure (hypertension) and is also used for heart failure. Lisinopril works by blocking the production of Angiotensin II, a hormone that narrows blood vessels. By inhibiting this process, the medication allows blood vessels to relax and widen, lowering blood pressure and reducing strain on the heart. Like all pharmaceuticals, Lisinopril can cause unintended effects, and some patients are concerned about its possible connection to hair loss. This article examines the scientific reports and biological theories surrounding this potential side effect.
Incidence and Reporting of Hair Loss
Hair loss, or alopecia, is explicitly listed as a possible side effect in the official prescribing information for Lisinopril. Data collected from clinical trials and post-marketing surveillance classify this occurrence as uncommon. The reported incidence rate of alopecia observed in controlled clinical trials is low, affecting less than 1% of patients using the medication.
This low percentage indicates that the vast majority of people taking Lisinopril will not experience drug-related hair thinning or loss. Despite the low frequency, case reports confirm a probable link between Lisinopril use and new-onset alopecia. These reports provide evidence that for a small, susceptible patient group, the medication can be the culprit.
The severity of the cardiovascular conditions Lisinopril treats means that any potential side effect must be weighed against the substantial therapeutic benefit. Hair loss is not considered a primary or frequent complaint among possible adverse reactions. When it occurs, it is often reported to a national adverse event database, contributing to the overall surveillance data.
How Lisinopril May Affect the Hair Cycle
The mechanism most commonly theorized when Lisinopril is implicated in hair loss is Telogen Effluvium (TE). TE is a diffuse, non-scarring type of hair shedding that occurs when a physical or emotional stressor prematurely pushes a large number of growing hairs into the resting phase. Normally, about 85-90% of hair follicles are in the growth phase (anagen), while only 10-15% are in the shedding phase (telogen).
A systemic drug like Lisinopril can act as a physiological shock, disrupting the normal hair growth cycle. The medication causes a greater proportion of follicles to prematurely enter the telogen phase, leading to noticeable shedding typically one to three months after starting the drug. This delay is typical for Telogen Effluvium because the affected hairs must complete the full telogen cycle before falling out.
The specific biological pathway by which ACE inhibitors trigger this follicular stress is still under investigation. Lisinopril targets the Renin-Angiotensin-Aldosterone System (RAAS), which has components present within the skin and the hair follicle. It is hypothesized that altering the balance of Angiotensin II and other peptides in this local system may indirectly affect the follicle’s ability to maintain its normal growth phase.
Another theory suggests the mechanism may involve an indirect effect on other hormones or inflammatory pathways regulated by the RAAS. For instance, interference with aldosterone levels could play a role in hair growth regulation. However, the drug does not permanently damage the hair follicle, meaning the hair loss associated with it is generally reversible once the trigger is removed.
Next Steps for Concerned Patients
Patients who suspect Lisinopril is causing hair thinning or shedding should schedule an appointment with their healthcare provider before changing their regimen. Stopping medication for high blood pressure or heart failure without medical supervision poses serious cardiovascular risks. The physician must perform a differential diagnosis to rule out other common, simultaneous causes of hair loss.
Hair loss can be triggered by many factors, including severe emotional stress, underlying thyroid issues, iron or nutrient deficiencies, or other systemic illnesses. The patient’s underlying condition, such as hypertension, can also contribute to physiological stress leading to Telogen Effluvium. After ruling out these alternatives, the doctor may conclude that Lisinopril is the probable cause.
If Lisinopril is confirmed as the trigger, the physician may recommend switching to an alternative drug class for blood pressure management, such as an Angiotensin Receptor Blocker (ARB). Case reports show that patients who switch from Lisinopril to an ARB, like losartan, have seen their alopecia resolve. When the medication is discontinued, the hair cycle resets, and new growth is typically observed within three to six months.