Losartan is a widely prescribed medication used to manage high blood pressure and treat heart failure. It belongs to a class of drugs called Angiotensin II Receptor Blockers (ARBs). ARBs work by preventing the hormone angiotensin II from binding to receptors in blood vessels, which allows blood vessels to relax and widen. This action lowers blood pressure and makes it easier for the heart to pump blood. For many patients beginning a new long-term medication, concerns arise about potential side effects, including whether Losartan might cause hair loss.
Losartan and the Evidence for Hair Loss
Clinical data from controlled trials and large-scale post-marketing surveillance suggest that hair loss is not a frequent side effect of Losartan. In pre-approval clinical studies, the overall incidence of adverse events was similar to that observed in patients taking a placebo. Hair loss, or alopecia, was not listed among the common side effects that occurred in two percent or more of patients treated with Losartan.
Cases of hair loss associated with Losartan are reported in the Food and Drug Administration Adverse Event Reporting System (FAERS), which collects voluntary reports. However, these reports remain infrequent relative to the millions of prescriptions issued. Post-market reports are considered anecdotal and do not establish a direct cause-and-effect relationship, as patients are often taking multiple medications or may have other underlying health conditions. Drug-induced hair shedding is classified as a rare event associated with this specific Angiotensin II Receptor Blocker.
The vast majority of individuals prescribed Losartan will not experience hair thinning or loss. For those few patients who do notice increased shedding, it is understood to be a potential consequence of individual sensitivity rather than a mechanism inherent to the drug class. Losartan’s main mechanism is focused on the cardiovascular system, making a direct impact on the hair follicle less likely.
Mechanisms of Drug-Induced Alopecia
Medications that affect hair growth interfere with the natural cycle of the hair follicle, which progresses through growth, transition, and resting phases. Drug-induced hair loss manifests through two primary mechanisms: Anagen Effluvium (AE) or Telogen Effluvium (TE).
Anagen Effluvium involves the abrupt cessation of cell division in the hair matrix, affecting actively growing hairs. This mechanism is associated with aggressive chemotherapeutic agents and results in rapid, widespread hair loss, often occurring within days or weeks of starting the drug.
Telogen Effluvium (TE) is the more common form of drug-induced alopecia and is the mechanism most likely linked to blood pressure medications like Losartan. This condition occurs when a significant number of growing (anagen) hairs are prematurely pushed into the resting (telogen) phase. Since the telogen phase lasts approximately three months, the noticeable increase in hair shedding often begins two to four months after starting the causative medication or changing its dosage.
In Telogen Effluvium, the hair loss is diffuse, meaning thinning is noticeable across the entire scalp. Antihypertensive drugs, including ACE inhibitors and beta-blockers, are known to occasionally trigger this delayed shedding pattern. If Losartan is confirmed as the cause, the hair follicle is not permanently damaged, and the hair growth cycle is expected to normalize once the body adjusts to the medication or the inciting factor is removed.
Managing Hair Loss Concerns While Taking Losartan
Any patient who suspects Losartan is contributing to increased hair shedding should schedule a consultation with their prescribing physician or cardiologist. Patients must never abruptly stop taking Losartan or any blood pressure medication without direct medical supervision. Suddenly discontinuing treatment for hypertension can lead to a dangerous spike in blood pressure, increasing the risk of serious events like stroke or heart attack.
The physician will begin the diagnostic process by ruling out more common causes of hair loss. This may involve blood work to check for nutritional deficiencies, such as low iron or zinc, or hormonal imbalances like thyroid issues. If other causes are excluded, the doctor will evaluate the timeline of the hair loss in relation to starting Losartan, which is a key step in diagnosing drug-induced Telogen Effluvium.
If the medication is confirmed or strongly suspected to be the source of the issue, the physician has several management options. These options include monitoring the situation to see if the shedding subsides as the body adapts to the drug, or potentially adjusting the dosage. Another approach is switching the patient to an alternative medication for blood pressure control. The doctor may recommend a different drug within the ARB class, like Valsartan, or an agent from a completely different antihypertensive class, such as a calcium channel blocker. The decision to change medication is a medical judgment based on the severity of the hair loss, the patient’s overall health, and the effectiveness of the current Losartan regimen.