Plasma donation, or plasmapheresis, is a medical procedure where blood is drawn, the plasma is separated and collected, and the remaining blood cells are returned to the donor with a saline solution. Plasma is the liquid portion of blood, composed mostly of water, proteins, salts, and nutrients. While generally safe, temporary side effects are common, with nausea being one of the most frequently reported symptoms. This reaction arises as the body adjusts to the temporary fluid loss and the introduction of anticoagulants.
Physiological Causes of Post-Donation Nausea
One common cause of feeling unwell is the vasovagal response, a nervous system reflex triggered by stress, anxiety, or the sight of the procedure itself. This reflex causes the vagus nerve to become overactive, resulting in a sudden, temporary drop in heart rate and blood pressure. The resulting brief reduction in blood flow to the brain produces symptoms like lightheadedness, sweating, pallor, and nausea.
Another mechanism unique to plasma donation is the citrate reaction. Citrate is added to the drawn blood to prevent clotting while it is being processed in the machine. A small amount of this anticoagulant is returned to the donor. Citrate works by binding temporarily to calcium ions in the bloodstream, causing a short-term reduction in ionized calcium levels, known as hypocalcemia.
This temporary drop in ionized calcium increases nerve excitability, leading to symptoms such as a metallic taste, tingling sensations around the lips and fingertips, muscle twitching, and nausea. The severity of this reaction is often directly related to the volume of plasma collected and the rate at which the citrate-containing blood is returned to the body.
Temporary fluid loss and metabolic changes also contribute to nausea. Since plasma is mostly water, removing a significant volume causes a transient state of hypovolemia, or reduced blood volume, and dehydration. This fluid decrease can cause a slight drop in blood pressure, mimicking the effects of the vasovagal response. Additionally, if a donor has not eaten recently, the stress of the procedure combined with fluid loss can lead to lower blood sugar levels, which also manifests as dizziness and nausea.
Preparation to Minimize Risk
Taking proactive steps before arriving at the donation center significantly reduces the likelihood of post-donation nausea. Proper hydration is the most effective preventative measure, given the high water content of plasma. Donors should drink an extra 16 to 24 ounces of non-caffeinated fluid, such as water or an electrolyte beverage, in the hours leading up to their appointment.
Nutrition also plays a substantial role in maintaining stability. Eating a full meal rich in protein and iron within three hours of the appointment stabilizes blood sugar levels and energy reserves. Fasting or skipping a meal increases the risk of feeling faint or nauseous due to low blood sugar and general weakness.
For donors who experience anxiety, engaging in distraction techniques can be helpful. Some centers recommend applied muscle tension (AMT), where a donor repeatedly tenses the muscles in their legs, buttocks, and abdomen for short periods. This isometric exercise helps to momentarily raise blood pressure, counteracting the sudden drop associated with a vasovagal reaction.
Communicating with the phlebotomist about any previous adverse reactions or mild tingling sensations is a useful preventative step. Staff can adjust the flow rate of the apheresis machine, which moderates the amount of citrate being returned and helps the body manage the temporary drop in ionized calcium.
Immediate Steps for Recovery
If nausea or lightheadedness begins during or immediately after the donation, notify a staff member and assume a reclined position. Lying down with the feet elevated above the heart level encourages blood flow back to the brain, quickly alleviating symptoms related to low blood pressure. This position should be maintained until the feelings of discomfort have fully passed.
Once immediate symptoms subside, the focus shifts to replenishing lost fluids and nutrients. Drinking water or an electrolyte-rich sports drink restores the body’s fluid balance and addresses temporary dehydration. Consuming a small, bland, and easily digestible snack, such as crackers, pretzels, or a piece of fruit, helps restore blood sugar levels.
Donors should remain in the observation area for the recommended period, typically 10 to 15 minutes, and should not attempt to stand up quickly. When getting up, transition slowly from lying down to sitting, and then from sitting to standing, to allow the circulatory system time to adjust. Avoiding strenuous activity or heavy lifting for the rest of the day is advised to ensure complete recovery.
When Nausea Signals a Serious Issue
While most post-donation nausea is mild and quickly resolves with rest and fluids, certain symptoms indicate the reaction requires professional medical attention. Nausea that is immediately followed by forceful vomiting, or that persists for several hours after leaving the donation center, should be reported to the center staff or a healthcare provider.
Accompanying symptoms that signal a potentially serious issue include:
- Severe dizziness or a fainting episode (syncope).
- Muscle spasms that do not resolve.
- Difficulty breathing or chest pain.
- An irregular or rapid heart rate.
- Confusion.
These symptoms can occasionally be associated with complications such as a severe citrate reaction or an air embolism.
Donors who experience rapidly worsening or severe symptoms should not attempt to drive themselves home or “sleep it off.” The donation center staff are trained to manage these situations and will determine whether the issue can be managed on-site or if the donor needs to be transported to an emergency department for further evaluation.