Does Drinking Cause Low Blood Pressure?

Drinking alcohol does lower blood pressure in the short term, often within the first few hours after a drink. A large Cochrane review of randomized trials found that a moderate amount of alcohol dropped systolic blood pressure by about 5 to 6 mmHg within six hours. But the story flips: roughly half a day later, blood pressure rebounds and climbs above where it started. This biphasic pattern means alcohol can cause both low blood pressure and high blood pressure, depending on when you check.

The Two-Phase Blood Pressure Response

Alcohol’s effect on blood pressure is not a simple line going in one direction. It follows a distinct two-phase curve that has been confirmed across dozens of controlled trials. In the first phase, lasting up to about 12 hours after drinking, blood pressure drops. In the second phase, beginning around 13 hours after consumption, blood pressure rises above baseline levels.

A Cochrane systematic review pooling data from multiple randomized trials put numbers on this pattern. A medium dose of alcohol (roughly one to two standard drinks) lowered systolic pressure by about 5.6 mmHg and diastolic pressure by about 4 mmHg within six hours, while heart rate went up by about 5 beats per minute. Higher doses showed a similar but slightly less dramatic initial drop, with systolic pressure falling about 3.5 mmHg. But past the 13-hour mark, that same high dose pushed systolic pressure up by about 3.7 mmHg and diastolic by about 2.4 mmHg above baseline.¹

A separate study in people with normal blood pressure, using 24-hour ambulatory monitoring, observed a similar seesaw. Systolic and diastolic pressures each fell about 4 mmHg in the hours right after drinking, then rose by about 7 and 4 mmHg respectively later that night.² So the answer to the title question depends entirely on the time window. If you measure blood pressure shortly after someone has been drinking, it will often be lower. If you measure the next morning, it may be higher.

Why Alcohol Lowers Blood Pressure in the First Place

The initial blood-pressure drop is not one mechanism but several working together. The most immediate is vasodilation: alcohol causes blood vessels to relax and widen, reducing the resistance that blood meets as it flows through the body. At the molecular level, low-to-moderate amounts of alcohol stimulate the release of nitric oxide from the cells lining blood vessels, and nitric oxide is one of the body’s primary signals to relax vascular smooth muscle.³ Wider vessels mean less pressure on the arterial walls.

Alcohol is also a diuretic. It suppresses the release of vasopressin, the hormone that tells your kidneys to hold onto water. The result is increased urine output, which shrinks blood volume and lowers pressure. One study tracking fluid balance after alcohol consumption found significantly higher total urine output compared with water, with the effect becoming pronounced over several hours. The body eventually counterregulates by ramping vasopressin back up and retaining water, but in the interim, the fluid loss contributes to lower pressure.⁴

A third mechanism involves the baroreflex, the body’s built-in system for sensing blood pressure changes and adjusting accordingly. When blood pressure falls, the baroreflex normally triggers the heart to beat faster and blood vessels to constrict, pulling pressure back up. Alcohol blunts this response. In both healthy people and those with high blood pressure, alcohol reduced baroreflex sensitivity before any change in blood pressure or heart rate was detectable, meaning the body’s safety net is weakened before the pressure actually starts to fall.⁵ That combination of wider vessels, less fluid, and a dampened correction system is what makes post-drinking blood pressure noticeably lower.

Standing Up After Drinking and the Risk of Fainting

The biggest practical concern with alcohol-related low blood pressure is not what happens while you are sitting comfortably with a drink. It is what happens when you stand up. Orthostatic hypotension, the sharp drop in blood pressure that occurs when you shift from sitting or lying down to standing, is dramatically worsened by alcohol. Your body normally compensates for the gravitational pull of blood toward your legs by tightening blood vessels and speeding up your heart. Alcohol impairs exactly those compensatory reflexes.

Research simulating the cardiovascular stress of standing found that alcohol roughly doubled the drop in systolic blood pressure compared to a placebo session. During the placebo session, blood pressure held relatively steady under mild orthostatic stress and only fell meaningfully under strong stress. After alcohol, blood pressure fell at every level of stress, and the drop at peak stress was about 14 mmHg compared with only 7 mmHg on placebo.⁶ The researchers concluded that this impaired vasoconstriction helps explain alcohol-related fainting episodes, which are a real and underappreciated cause of falls and injuries.

You have probably experienced a mild version of this: standing up quickly after several drinks and feeling lightheaded or seeing spots. In most people this is brief and harmless. But in older adults, people on blood pressure medications, or anyone already prone to orthostatic drops, the combination can lead to falls, head injuries, or loss of consciousness. The risk is highest in the first few hours after drinking, exactly when the initial blood-pressure-lowering phase is strongest.

Heat, Saunas, and Other Amplifiers

Anything else that dilates blood vessels or lowers blood volume will stack on top of alcohol’s effects. Heat is the most common amplifier. A study measuring blood pressure during sauna use found that sauna bathing alone kept systolic pressure roughly at baseline. But when participants drank alcohol before entering the sauna, systolic pressure fell from about 136 to 113 mmHg, a drop of more than 20 points.⁷ The researchers noted an increased risk of clinically significant hypotension with this combination.

The same logic applies to hot tubs, hot showers, and exercising in warm weather. Heat pushes blood toward the skin for cooling, which reduces the volume available for maintaining core blood pressure. Alcohol does something very similar through vasodilation. Together, they can drop pressure to the point where you feel dizzy, nauseated, or faint. Dehydration from sweating compounds the problem further by shrinking blood volume on top of alcohol’s diuretic effect.

This is also why drinking on an empty stomach can produce a bigger blood pressure dip. Food in the stomach slows alcohol absorption, spreading its effects over a longer period. Without that buffer, alcohol enters the bloodstream more quickly, and the vasodilation and fluid shifts happen in a more concentrated burst.

Chronic Heavy Drinking Raises Blood Pressure, Not Lowers It

If you are asking whether drinking causes low blood pressure because you drink regularly and have noticed low readings, the picture changes considerably. While a single drinking session temporarily lowers blood pressure, habitual heavy drinking is one of the strongest modifiable risk factors for hypertension. A meta-analysis found that chronic alcohol consumption was associated with a high incidence of high blood pressure in both men and women, with the risk in women beginning at what many people would consider moderate intake levels.⁸

The mechanisms behind chronic alcohol-induced hypertension are largely the opposite of what happens acutely. High concentrations of alcohol and long-term exposure impair the endothelium’s ability to produce nitric oxide, so instead of promoting vasodilation, chronic heavy drinking tips the balance toward vascular stiffness and constriction.³ The body also adapts to repeated exposure by upregulating stress hormones and sympathetic nervous system activity, both of which keep pressure elevated between drinking episodes.

A population-level study found that in men, systolic and diastolic blood pressure climbed by about 0.9 and 0.6 mmHg per daily drink, respectively. In women, those who had two or more drinks per day had systolic readings about 2 mmHg higher and diastolic about 1 mmHg higher than nondrinkers. The relationship was stronger in older men compared to younger men, and in smokers of both sexes compared to nonsmokers.⁸ These are averages, and the cumulative effect builds over time, so years of daily drinking can add up to a clinically meaningful increase.

When Chronic Drinking Does Cause Lasting Low Blood Pressure

There is an exception to the chronic-drinking-equals-hypertension pattern, and it involves nerve damage. Long-term heavy alcohol use can injure the autonomic nervous system, the network of nerves that controls involuntary functions like heart rate, digestion, and blood vessel tone. When these nerves are damaged, a condition called dysautonomia, the body loses its ability to properly regulate blood pressure, and orthostatic hypotension can become a persistent daily problem rather than a temporary post-drinking one.

A published case report described a patient with a long history of alcoholism and uncontrolled diabetes who presented with chronic orthostatic hypotension and peripheral neuropathy. Even after his diabetes was brought under control and other risk factors were managed, his blood pressure instability persisted, pointing to alcohol-related autonomic dysfunction as the underlying cause.⁹ This is a single case, so it does not tell us how common this specific presentation is, but alcohol-related autonomic neuropathy is a recognized complication of long-term heavy drinking, especially when combined with nutritional deficiencies that often accompany alcohol use disorder.

The distinction matters for anyone who has been a heavy drinker for years and notices that they feel faint or dizzy when standing. That symptom could reflect the normal acute biphasic effect if they have recently been drinking. But if it happens consistently, even on days without alcohol, it may signal autonomic nerve damage that warrants medical evaluation.

Who Is Most Vulnerable to Alcohol-Related Blood Pressure Drops

Not everyone experiences the same degree of blood pressure lowering after drinking. Several factors make some people more susceptible:

Older adults: Aging naturally stiffens arteries and weakens baroreflex responses, so the added impairment from alcohol hits harder. The association between alcohol and blood pressure changes is stronger in older men than in younger men.
People on blood pressure medications: If you are already taking a drug that lowers blood pressure through vasodilation, diuresis, or reduced heart rate, alcohol adds a second push in the same direction. The combined effect can cause symptomatic hypotension that neither the drug nor the alcohol would produce alone.
Smokers: The relationship between alcohol and elevated blood pressure is stronger in smokers of both sexes compared with nonsmokers, but the acute vasodilatory phase may also produce larger initial dips in people whose baseline vascular tone is already altered by nicotine’s effects.
People who are dehydrated or fasting: Starting from a lower blood volume or absorbing alcohol more rapidly amplifies both the fluid-loss and vasodilation components of the initial blood pressure drop.

Women appear to face a hypertension risk from chronic alcohol at lower intake levels than men, though the acute biphasic pattern itself has been observed across both sexes in controlled trials.⁸

Does the Type of Drink Matter

People often wonder whether wine, beer, or spirits differ in their effect on blood pressure. The ethanol itself is the primary driver of both the acute drop and the chronic rise, regardless of what beverage it comes in. But there is an interesting wrinkle in the evidence regarding wine.

A crossover trial had participants consume red wine, dealcoholized red wine (same grape polyphenols with the alcohol removed), or gin, each for four weeks. Red wine and gin both contained 30 grams of alcohol per day. After the dealcoholized red wine period, systolic and diastolic blood pressure decreased significantly, and these decreases correlated with increases in circulating nitric oxide. Regular red wine and gin did not produce the same sustained reductions.³

The implication is that the polyphenols in red grapes can lower blood pressure on their own, but that the alcohol in wine counteracts this benefit when consumed chronically. So if someone drinks red wine nightly and assumes they are getting a blood-pressure benefit from the polyphenols, the alcohol is likely canceling that out or turning it into a net increase over time. Grape juice or dealcoholized wine would deliver the polyphenol effect without the countervailing alcohol effect.

Alcohol and Blood Pressure Medications

If you take medication for high blood pressure and drink socially, the interaction is worth understanding in concrete terms. Many common blood pressure drugs work through the same pathways alcohol affects. ACE inhibitors and calcium channel blockers promote vasodilation. Diuretics reduce blood volume. Beta-blockers slow heart rate and reduce the force of heart contractions. Alcohol pushes on these same levers, so the combined effect can overshoot the target.

The practical result is that a glass of wine that would cause a barely noticeable pressure dip in someone not on medication could cause lightheadedness, fatigue, or fainting in someone whose blood pressure is already being pharmacologically lowered. The risk is highest within the first few hours of drinking, when the acute vasodilatory phase is strongest. This does not mean you can never drink on blood pressure medication, but it does mean the margin for error is narrower, especially with higher doses of alcohol, and especially when standing up, exercising, or being in hot environments.

Alcohol can also interfere with how consistently blood pressure medications work. The rebound increase in blood pressure that occurs 13 or more hours after drinking means that a morning blood pressure reading after a night of heavy drinking may actually be higher than it would otherwise be, even while the medication is active. For someone whose doctor is adjusting their drug dose based on home blood pressure readings, regular drinking introduces noise that can make the readings unreliable in both directions.

Hangover Blood Pressure

The rebound phase of alcohol’s biphasic effect coincides roughly with what most people experience as a hangover. Blood pressure tends to be above baseline by the time you wake up the morning after heavy drinking, and this elevation can persist for most of the day. The Cochrane review data showed that more than 13 hours after high-dose consumption, systolic pressure was up by about 3.7 mmHg and heart rate remained about 3 beats per minute above normal.¹

For most healthy people, a few mmHg increase the day after drinking is not dangerous. But for someone with borderline or uncontrolled hypertension, repeated cycles of post-drinking blood pressure spikes represent a pattern of cardiovascular stress. And if someone who drinks heavily most nights is getting their blood pressure checked in the morning, their readings may consistently reflect this rebound elevation, potentially leading to a diagnosis of hypertension that is partly alcohol-driven but not recognized as such.

Dehydration during a hangover can, paradoxically, coexist with the elevated blood pressure. Your blood volume may be low from alcohol’s diuretic effect, but compensatory mechanisms like increased sympathetic nerve activity and stress hormone release push pressure up anyway. This is why some people feel both dehydrated and headachy in a way that feels like high-pressure symptoms at the same time. Rehydrating and giving the body time to reset its fluid balance resolves both issues within a day for occasional drinkers, though the timeline stretches longer for people who drink heavily on consecutive days.