A high pH in your body, called alkalosis, means your blood has become more alkaline than normal. Healthy blood pH sits between 7.35 and 7.45, with an average of 7.40. When it rises above 7.45, the balance tips toward alkalosis, and the causes range from something as simple as breathing too fast during a panic attack to ongoing medication use or persistent vomiting.
Your body has two main ways to regulate pH: your lungs control how much carbon dioxide you exhale, and your kidneys control how much bicarbonate (a natural base) stays in your blood. When either system gets thrown off, pH climbs. The specific cause determines whether it’s classified as respiratory or metabolic alkalosis.
Breathing Too Fast Blows Off Too Much CO2
Carbon dioxide is mildly acidic. Every time you exhale, you’re removing acid from your blood. Normally this keeps things balanced. But when you breathe faster and deeper than your body’s metabolism requires, you blow off more CO2 than your tissues are producing, and blood pH rises.
This is respiratory alkalosis, and hyperventilation is its defining feature. Common triggers include anxiety or panic attacks, high altitude (where lower oxygen levels drive faster breathing), fever, pain, and certain lung conditions like pneumonia or pulmonary embolism. Even being on a mechanical ventilator set too aggressively can cause it. In most cases, slowing your breathing or addressing the underlying trigger brings CO2 levels back to their normal range of 35 to 45 mmHg, and pH drops back down.
Your kidneys begin compensating almost immediately by dumping extra bicarbonate into the urine. Specialized cells in the kidney’s collecting ducts detect the shift and start excreting the excess base. This compensation takes hours to days to fully kick in, which is why a brief episode of hyperventilation feels unpleasant but rarely becomes dangerous.
Losing Stomach Acid Through Vomiting
Your stomach produces hydrochloric acid. When that acid leaves the body through vomiting or through a tube draining the stomach, you lose acid without the normal downstream process that would reabsorb it. The cells lining the stomach generate acid on one side and release bicarbonate into the bloodstream on the other. Normally, when acid reaches the intestines, the body reclaims that bicarbonate. Severe or prolonged vomiting short-circuits this loop, leaving excess bicarbonate circulating in your blood and pushing pH upward.
The problem compounds itself. Losing stomach fluid also means losing chloride and water, which shrinks your blood volume. Your body responds by activating hormonal systems that aggressively hold onto sodium in the kidneys. A side effect of that sodium retention is increased potassium and acid excretion, which makes the alkalosis worse and harder to reverse, even after the vomiting stops. This is one reason prolonged vomiting from conditions like bowel obstruction, bulimia, or severe morning sickness can cause a stubborn rise in pH.
Low Potassium and High pH Feed Each Other
Potassium levels and blood pH are tightly linked. When potassium drops too low, your cells swap: hydrogen ions (acid) move from the blood into cells to replace the missing potassium, pulling acid out of circulation and raising blood pH. At the same time, the kidneys respond to low potassium by excreting more acid into the urine, further reinforcing the alkalosis.
This relationship also works in reverse. Alkalosis itself causes the kidneys to waste more potassium, creating a feedback loop where low potassium and high pH keep making each other worse. Anything that depletes potassium, including diarrhea, certain medications, heavy sweating, or poor dietary intake, can set this cycle in motion. Correcting alkalosis often requires fixing the potassium deficit first.
Diuretics and Other Medications
Loop and thiazide diuretics, commonly prescribed for high blood pressure and heart failure, are among the most frequent medication-related causes of alkalosis. These drugs work by blocking salt reabsorption in the kidneys, which increases urine output. But they also cause the kidneys to lose chloride, potassium, and fluid, all of which promote bicarbonate retention and a rise in pH. The resulting alkalosis follows the same pattern as vomiting: volume depletion activates hormonal systems that hold onto sodium at the cost of dumping potassium and acid.
Other medications can contribute too. High-dose corticosteroids mimic the effects of excess aldosterone, driving potassium loss and acid excretion. Laxative overuse depletes potassium through the gut. Even something as seemingly benign as calcium carbonate supplements or antacids, taken in large amounts, can trigger a condition called milk-alkali syndrome. This typically occurs when calcium intake exceeds 4 grams per day, though cases have been reported with as little as 1 gram daily. The result is a combination of high calcium, metabolic alkalosis, and kidney damage.
Excess Aldosterone and Hormonal Causes
Aldosterone is a hormone that tells the kidneys to hold onto sodium. When aldosterone levels are abnormally high, whether from an adrenal gland tumor, kidney artery narrowing, or other conditions, the kidneys aggressively reabsorb sodium. This creates a negatively charged environment in the kidney tubules that traps positively charged particles, including both potassium and hydrogen ions, flushing them into the urine. The net effect is low potassium and high pH.
Because the underlying hormone imbalance persists, this type of alkalosis doesn’t correct on its own with fluids the way vomiting-related alkalosis often does. It requires treating the hormonal excess directly.
What High pH Feels Like
Mild alkalosis often produces vague symptoms that are easy to dismiss: light-headedness, nausea, tingling or numbness in the fingers and around the mouth, and a general feeling of anxiety. The tingling happens because alkalosis lowers the level of available calcium in the blood. Calcium is still present, but high pH causes it to bind more tightly to proteins, leaving less of the “free” calcium your nerves and muscles need to function normally.
As pH climbs higher, symptoms become more pronounced. Muscle twitching, cramping, and spasms (particularly in the hands and feet) can develop. Confusion, dizziness, weakness, and tremors point to the nervous system struggling with the electrolyte disruption. In severe cases, alkalosis can progress to seizures, dangerous heart rhythm disturbances, or loss of consciousness. The cardiac risk comes largely from the combined effect of low potassium and low available calcium, both of which destabilize the heart’s electrical system.
How the Body Tries to Correct Itself
Your body has built-in buffers that work to pull pH back toward 7.40. When the problem starts in the lungs (respiratory alkalosis), the kidneys compensate by excreting more bicarbonate. When the problem is metabolic, the lungs compensate by slowing breathing slightly, retaining more CO2 to add acid back to the blood. These compensatory mechanisms are effective but limited. They can blunt the pH shift, but they rarely normalize it completely without the underlying cause being addressed.
The kidneys are particularly important in long-term pH regulation. Specialized cells in the collecting ducts actively secrete bicarbonate into the urine when blood pH is too high. This response begins within minutes but reaches full capacity over one to three days, which is why acute alkalosis tends to cause more noticeable symptoms than a slow, chronic rise.