Based on NIH | Does losartan increase the risk of dizziness, fainting, or low blood pressure during exercise?

Losartan can cause dizziness and low blood pressure, and these effects may be more noticeable during exercise especially if you are dehydrated, overheated, or starting therapy or a dose increase. Dizziness is a known side effect, and low blood pressure (hypotension) and fainting (syncope) have been reported, although serious events are uncommon. ^{[1] [2]}

How losartan might lead to dizziness or fainting

• Blood pressure lowering: Losartan lowers blood pressure by blocking angiotensin II’s effects; this can occasionally reduce pressure too much in some people, leading to lightheadedness or fainting. ^[1]
• Exercise and dehydration: Sweating heavily, not drinking enough fluids, or heat exposure during workouts can further drop blood pressure while on losartan, making dizziness more likely. ^[3]
• Orthostatic effects: Standing up quickly or sudden position changes can cause orthostatic hypotension (a temporary BP drop), which has been reported with losartan. ^[4]

How common are these symptoms?

• Dizziness: In clinical trials, dizziness occurred slightly more often with losartan than with placebo (about 2.4% vs 1.3%), indicating it’s a recognized but generally mild side effect. ^[2]
• Hypotension and syncope: Low blood pressure and fainting are listed adverse events; while they are not among the most frequent effects, they can occur, particularly in susceptible individuals (e.g., volume-depleted, on diuretics, or starting therapy). ^{[1] [4]}

Exercise while taking losartan: practical guidance

• Hydrate before and during workouts: Adequate fluids help maintain blood volume and reduce the risk of exercise‑related BP drops and lightheadedness. ^[3]
• Monitor how you feel: If you feel dizzy, stop, sit or lie down, and allow symptoms to pass; seek medical advice if episodes recur or are severe. ^[1]
• Warm up and cool down: Gradually ramping intensity and avoiding sudden stops can help stabilize blood pressure during sessions. ^[5]
• Check home blood pressure: Tracking readings around exercise times can help you and your clinician adjust dosing if needed. ^[6]
• Avoid excessive heat and sudden position changes: These can worsen drops in blood pressure during activity. ^[4]
• Discuss adjustments if you increased exercise: Expanding your training routine can improve blood pressure control over time, and your clinician may consider medication adjustments as fitness improves. ^[5]

Who may be at higher risk

• Volume depletion: Heavy sweating, diarrhea, vomiting, or aggressive diuretic use can increase the chance of hypotension on losartan. ^[3]
• Combination pills with diuretics (e.g., losartan/HCTZ): Diuretics increase fluid loss and can raise the risk of low blood pressure, especially in hot weather or intense exercise. ^{[7] [8]}
• Pre-existing autonomic or cardiovascular conditions: People with orthostatic intolerance or certain cardiac conditions may be more sensitive to BP-lowering effects. ^[4]

When to seek medical help

• Persistent or severe dizziness, fainting, or very low readings: These warrant prompt medical review to consider dose changes or timing adjustments. ^[1]
• Signs of dehydration or sudden weight changes: Swelling or unexplained weight gain can signal fluid issues and should be evaluated. ^[1]
• New palpitations or chest pain: Report immediately, as these symptoms require medical assessment. ^[4]

Bottom line

• It’s reasonable to expect mild dizziness in a small percentage of people on losartan, and exercise especially with dehydration or heat can make this more noticeable. ^{[2] [3]}
• Serious low blood pressure or fainting is uncommon but possible; good hydration, gradual training progression, and symptom monitoring significantly lower the risk. ^{[1] [5]}
• Work with your clinician to tailor dosing and timing around your exercise routine, and review any recurrent symptoms or low readings. ^{[6] [1]}

Quick tips for safer workouts on losartan

• Drink water regularly before, during, and after exercise. ^[3]
• Start sessions with a warm-up and end with a cool-down. ^[5]
• Pause and lie down if dizzy; resume only when stable. ^[1]
• Track BP at home and share trends with your clinician. ^[6]
• Be cautious in hot environments and avoid sudden standing after rest. ^[4]