Vomiting is a protective function that rids the body of viruses, bacteria or toxins, such as poisons. Prolonged vomiting can cause dehydration, and in some cases, an electrolye imbalance. Electrolytes are minerals or simple chemicals -- such as sodium, potassium and bicarbonate -- that carry a small electrical charge. They are essential to a variety of body processes, including water balance and muscle contractions. Infants, young children and seniors are particularly susceptible to developing an electrolyte imbalance due to prolonged vomiting.
The blood normally has a near-neutral pH, meaning it is neither too acidic nor too basic. Charged hydrogen particles are primarily responsible for the acidic nature of the blood. Acidic hydrogen is counterbalanced primarily by the alkaline electrolyte bicarbonate to maintain a near-neutral blood pH. With vomiting, acidic hydrogen particles are lost via the stomach acid that is thrown up. In cases of prolonged vomiting, the body sometimes cannot compensate for the loss of hydrogen particles. This may lead to the pH becoming too alkaline, with a relative excess of the electrolyte bicarbonate. When the pH of the blood is abnormal, the levels of other electrolytes may become imbalanced as well.
When prolonged vomiting leads to dehydration and an excessively alkaline pH, the body responds with a series of complex mechanisms aimed at restoring both water and pH balance. As a result of these mechanisms, the level of the electrolyte potassium in the blood often decreases -- a condition called hypokalemia. A low potassium level usually develops only when vomiting is severe enough to cause dehydration.
Signs and Symptoms
Vomiting severe enough to cause dehydration and an electrolyte imbalance may cause other symptoms. Since potassium is needed for normal muscle function, an extremely low level may cause muscle weakness, twitching or cramping. Excess bicarbonate can lead to a slower-than-normal breathing rate. Common signs and symptoms of dehydration include dizziness, low blood pressure, reduced urine production and dry mouth. In severe cases, confusion may occur.
Prevention and Treatment
Vomiting that occurs only once or twice is generally not a problem. However, repeated vomiting and an inability to keep down food or fluids can quickly lead to electrolyte imbalances and dehydration. Taking small sips of beverages that have electrolytes in them, such as electrolyte-replacement and sports drinks, can help prevent both dehydration and electrolyte imbalances.
Call the doctor right away if no food or fluid can be kept down and there are signs of possible dehydration. Also seek medical help right away if the vomiting is accompanied by a fever, moderate to severe pain in the abdomen, or if the vomited material smells like feces, or contains blood or particles that look like coffee grounds.