Specialist Explains Why Dangerous Low Blood Pressure Cases Are Increasing in Japan

Low blood pressure is often casually seen as something that just requires a bit of rest, but medical professionals view it very differently

Dr. Yoshimasa Goto, director of Goryokai Clinic Shirokanetakanawa, warns: “A drop in blood pressure is a dangerous condition in which blood flow to the brain, heart, and kidneys becomes insufficient. It can lead to fainting, falls, and in the worst case, can be life-threatening.” (The following comments are from Dr. Goto.)

In general, people tend to believe that “high blood pressure is dangerous, but low blood pressure is fine.” In recent years, preventive medicine has strengthened the trend toward stricter blood pressure control. However, in clinical practice, there are many cases where blood pressure dropping too low requires emergency response.

“If it is temporary, it may only cause lightheadedness or fatigue. However, if low blood pressure persists, it can lead to serious consequences such as fainting-related falls and fractures, myocardial ischemia, and reduced kidney function. In elderly patients especially, fractures can trigger long-term bedridden conditions,” he says.

Blood pressure is the force that delivers blood to organs throughout the body. If it drops too much, it affects life-sustaining functions. Why are more people experiencing low blood pressure now? There are three major factors.

1) Multiple use of antihypertensive drugs

“In recent years, hypertension treatment often targets below 130/80 mmHg. While this is effective for preventing stroke and myocardial infarction, in elderly, thin, or kidney-impaired patients, the medication can sometimes be too strong.”

Dr. Goto continues:

“In older adults, blood vessels lose elasticity and the heart’s ability to pump blood weakens. As a result, even systolic blood pressure around 110 or 100 mmHg may not deliver enough oxygen and nutrients to the brain, kidneys, and muscles. You cannot judge safety by numbers alone.”

2) Chronic dehydration

“As people age, they become less aware of thirst. When this combines with indoor dryness, sweating, loss of appetite, and use of diuretics, body fluid volume can decrease without the person noticing. This reduces circulating blood volume and lowers blood pressure. Dehydration occurs not only in summer but also in spring and winter. Waiting until you feel thirsty is already too late.”

3) Decline in autonomic nervous system function

“People with long-term diabetes, Parkinson’s disease, or prolonged bed rest have weakened mechanisms that regulate blood pressure when standing. As a result, orthostatic hypotension becomes more likely.”

He notes that falls are common right after waking up or standing up in the bathroom.

“Elderly individuals may also experience postprandial hypotension, where blood pressure drops after meals as blood flows to the digestive system. Strong sleepiness or dizziness after eating should not be ignored.”

Dangerous combinations

What modern hypertension treatment increasingly emphasizes is suppressing the morning surge, a sharp rise in blood pressure in the early morning. Around waking time, the sympathetic nervous system becomes highly active, and this is considered a high-risk period for strokes and heart attacks.

“Suppressing the early-morning rise in blood pressure is important. However, if medication is strengthened too much, the problem arises that blood pressure drops too much during the day or at night,” he explains.

As a result of excessive blood pressure reduction, symptoms such as daytime dizziness, severe post-meal drowsiness, falls during nighttime bathroom trips, and lightheadedness upon waking can occur.

“Modern hypertension treatment is a balancing act—we want to lower it in the morning, but not let it drop too much at night.”

Current mainstream treatment involves combining drugs such as ARBs (which lower blood pressure by inhibiting hormones that constrict blood vessels), calcium channel blockers (which lower blood pressure by dilating blood vessels), and diuretics (which reduce blood pressure by eliminating excess water and salt).

In patients with heart failure or chronic kidney disease, additional medications may be used, such as SGLT2 inhibitors (which excrete glucose and water in urine and protect the heart and kidneys) and MRAs (which suppress hormones that cause the body to retain salt and water, reducing strain on the heart and blood vessels).

“While blood pressure management has become more precise, the flip side is that multiple mechanisms can cause blood pressure to drop suddenly. In particular, caution is needed with combinations such as diuretics + SGLT2 inhibitors + heavy sweating on hot days.”

If the following symptoms are observed, they should not simply be dismissed as fatigue:

・Lightheadedness

・Cold sweat

・Vision becoming white or narrowing

・Strong post-meal drowsiness

・Feeling like you might collapse upon waking

・Sensation of fading consciousness

“In some cases, it can be difficult to distinguish from hypoglycemia or arrhythmia. Anyone who has even once nearly fainted should seek medical attention early.”

The basic preventive measures recommended by Dr. Goto are:

・Measure blood pressure within 1 hour after waking and before sleep

・Consult a doctor if systolic blood pressure stays below 100 mmHg

・Maintain adequate hydration (about 1.2–1.5 liters per day)

・Avoid standing up suddenly

・Avoid intense activity for 30 minutes to 1 hour after meals

・Avoid extreme salt restriction or undernutrition

Many people attribute fatigue, morning sluggishness, or post-meal sleepiness to aging. However, dangerous low blood pressure may be hiding behind these symptoms.

Dr. Goto concludes:

“People tend to worry only about high blood pressure, but blood pressure that is too low is also dangerous. Those taking medication and elderly individuals, in particular, should review their condition.”

Blood pressure is dangerous not only when it is too high, but also when it is too low. This understanding is likely to become increasingly important in Japan going forward.