Raising a low diastolic blood pressure starts with increasing your blood volume through fluids and salt, then layering in physical strategies and, if needed, medication. Diastolic pressure (the bottom number in a blood pressure reading) reflects the pressure in your arteries between heartbeats, and when it drops too low, your heart muscle and organs may not get adequate blood flow. A diastolic reading consistently below 60 mmHg is generally considered low, though symptoms matter more than any single number.
Low diastolic pressure can cause dizziness, fatigue, lightheadedness, and fainting. It also carries a real physiological risk: your heart receives most of its own blood supply during the diastolic phase, so chronically low diastolic pressure can impair coronary perfusion and, over time, promote subtle heart muscle damage, especially if you have any degree of coronary artery disease.
Why Your Diastolic Pressure Might Be Low
The most common culprit is simple dehydration, which reduces total blood volume and leaves less pressure in your arteries between beats. But several other conditions can drive diastolic pressure down. Prolonged bed rest, pregnancy, and certain medications (particularly blood pressure drugs, diuretics, and some antidepressants) all qualify. Conditions affecting the autonomic nervous system, the network that controls involuntary functions like heart rate and blood vessel tone, are another major category. Parkinson’s disease, diabetes-related nerve damage, and a rare condition called multiple system atrophy can all impair your body’s ability to tighten blood vessels when it needs to.
Nutrient deficiencies play a role too. Vitamin B12 deficiency can cause a type of nerve damage that weakens your body’s ability to adjust vascular resistance, leading to blood pooling in your legs and a drop in both cardiac output and blood pressure. In documented cases, B12 supplementation completely resolved the hypotension.
Postprandial hypotension, a drop in blood pressure after eating, is particularly common in older adults. Blood diverts to the digestive system after a meal, and if your body can’t compensate by constricting blood vessels elsewhere, your diastolic pressure falls.
Drink More Water (and It Works Fast)
Increasing fluid intake is the single most accessible way to raise diastolic pressure. Research published in the American Heart Association’s journal Circulation found that drinking 500 mL (about 16 ounces) of water raised diastolic blood pressure from 75 to 79 mmHg in healthy subjects, a statistically significant increase. The effect came from increased peripheral resistance, meaning the added fluid volume helped blood vessels maintain more tone. Interestingly, systolic pressure barely changed, making water intake a particularly targeted strategy for the diastolic number.
For people with recurring low blood pressure or fainting episodes, a daily fluid target of 2 to 3 liters is a standard recommendation. That’s roughly 8 to 12 cups spread throughout the day. Drinking a large glass of water 15 to 30 minutes before standing up or before meals can help blunt the drops that happen during those transitions.
Increase Your Salt Intake
Salt helps your body retain water, which expands blood volume. If you’ve been told your whole life to cut back on sodium, this advice may feel counterintuitive, but for people with genuinely low blood pressure, more salt is therapeutic. Adding salt to meals, eating salty snacks, or using electrolyte drinks can all help. The goal isn’t to eat excessively salty food but to stop avoiding sodium and actively include it. Your target depends on your overall health, but many people with hypotension benefit from 3 to 5 grams of sodium per day, well above the standard recommendation for the general population.
Physical Maneuvers for Quick Relief
When you feel diastolic pressure dropping (dizziness, graying vision, lightheadedness), specific physical counterpressure maneuvers can buy you time by forcing blood back toward your heart and brain. The American Heart Association recommends several:
- Leg crossing with muscle tensing: Cross your legs and tighten your leg, abdominal, and buttock muscles simultaneously. This works lying down or standing.
- Squatting: Drop into a squat and tense your lower body and abdominal muscles. Stay there until symptoms pass, then stand slowly.
- Isometric handgrip: Grip your hands together, fingers interlocked, and pull your arms in opposite directions with maximum force.
- Fist clenching: Clench your fist as hard as you can, with or without holding an object.
These maneuvers are temporary fixes. They’re most useful for preventing a faint when you feel warning signs, not as a long-term treatment strategy.
Compression Garments
Waist-high compression stockings physically prevent blood from pooling in your legs and abdomen, which is one of the main mechanisms behind low diastolic pressure in people with autonomic dysfunction. Most experts in dysautonomia recommend stockings rated at 20 to 30 mmHg or 30 to 40 mmHg of pressure. The key detail: they need to be waist-high, not knee-high. Knee-high stockings simply push the pooling problem up to your thighs, which doesn’t solve much. Abdominal binders can serve a similar function by compressing the large venous reservoir in your abdomen.
Compression garments work best when combined with fluid and salt loading. Worn during the day and removed at night, they can meaningfully reduce dizziness and improve standing tolerance.
Caffeine’s Modest Effect
Coffee raises diastolic blood pressure, but not by much. A meta-analysis of controlled trials found that regular coffee drinking increased diastolic pressure by an average of 1.2 mmHg compared to controls. Each additional cup contributed roughly 0.5 mmHg to diastolic pressure. The mechanism involves caffeine blocking receptors that normally dilate blood vessels, which increases vascular resistance. Decaffeinated coffee had no effect, confirming caffeine is the active ingredient.
For someone with mildly low diastolic pressure, a cup or two of coffee before activities that trigger symptoms (like prolonged standing or meals) can provide a small boost. It’s not a primary treatment, but it’s a reasonable addition to other strategies.
Eating Patterns That Help
Large meals pull blood toward your digestive tract and can cause significant diastolic drops, especially in older adults. Eating smaller, more frequent meals reduces this effect. Cutting back on high-carbohydrate meals also helps, since carbohydrates trigger a stronger digestive blood flow response than protein or fat. Some people find that lying down for 15 to 30 minutes after eating prevents the worst of the postprandial drop.
When Lifestyle Changes Aren’t Enough
If increased fluids, salt, compression, and physical maneuvers don’t resolve your symptoms, medications are the next step. The first-line prescription is typically a mineralocorticoid that works as a volume expander, helping your kidneys retain sodium and water to increase blood volume. If that’s insufficient, a second-line option is a medication that directly tightens blood vessels by stimulating receptors in the vascular wall. Both require monitoring because they can cause excessive blood pressure elevation when lying down.
Before pursuing medications, it’s worth checking for correctable underlying causes. A B12 level, thyroid panel, and review of your current medications can reveal reversible factors. Many common drugs, including those for enlarged prostate, depression, and heart conditions, lower diastolic pressure as a side effect. Sometimes the fix is adjusting or switching an existing prescription rather than adding a new one.
Positioning and Daily Habits
Elevating the head of your bed by 10 to 20 degrees (using blocks under the headboard, not extra pillows) helps your body retain fluid overnight by reducing the kidney’s tendency to dump sodium and water while you’re lying flat. This means you start the day with more blood volume.
Standing up slowly sounds obvious, but doing it deliberately, pausing at the edge of the bed for 30 seconds, then standing while tensing your leg muscles, can prevent the sudden diastolic drop that causes morning dizziness. Avoid prolonged standing in one position. If you have to stand for a long time, shift your weight, rise on your toes, and cross your legs periodically to keep blood moving upward.
Hot environments, including hot showers and baths, dilate blood vessels and lower diastolic pressure. Keeping shower temperatures moderate and limiting time in hot tubs or saunas can prevent unnecessary drops.