Quick Answer
The primary reason plasma donation makes you cold is that saline solution returned to your body is at room temperature (~68°F/20°C), which is significantly below your body temperature of 98.6°F (37°C). Each apheresis cycle returns this cooled saline into your bloodstream, gradually lowering your core body temperature. Other factors include sitting still for 45-90 minutes, air conditioning in the center, and temporary blood volume reduction.
The Main Cause: Room-Temperature Saline Return
During plasmapheresis, the donation machine works in cycles:
- Draw cycle: Blood is drawn from your arm into the machine
- Separation: A centrifuge separates plasma from red blood cells
- Return cycle: Red blood cells are mixed with saline solution and returned to your body
Here is the key: that saline solution is stored at room temperature, approximately 68°F (20°C). Your blood and body are at 98.6°F (37°C). That is a 30-degree difference every single cycle.
A typical plasma donation involves 5-8 draw/return cycles. Each time, room-temperature saline enters your bloodstream, mixes with your warm blood, and slightly lowers your core temperature. Over the course of a 45-90 minute donation, this cumulative cooling effect is noticeable — and sometimes significant.
The Math Behind the Chill
During a standard donation, approximately 690-880 mL of plasma is removed and replaced with a similar volume of saline. That means nearly a liter of 68°F fluid is gradually introduced into your 98.6°F circulatory system. Your body has to work to heat this fluid, burning calories and diverting blood flow to maintain core temperature.
Other Contributing Factors
While saline temperature is the primary cause, several other factors compound the cold feeling during plasma donation:
1. Sitting Still for Extended Periods
Plasma donation requires you to sit relatively motionless for 45-90 minutes. Without muscle movement generating heat, your body gradually cools. This is the same reason you feel cold sitting at a desk for hours without moving.
2. Air Conditioning in the Center
Plasma centers typically keep their facilities cool (68-72°F) for multiple reasons:
- Equipment operates better at lower temperatures
- Staff wearing gloves and moving around stay comfortable
- Cooler temps help prevent donors from feeling faint
- Cleanliness standards require good air circulation
3. Temporary Blood Volume Reduction
Even though red blood cells are returned, there is a brief period during each draw cycle when your blood volume is slightly reduced. Lower blood volume means less warm fluid circulating to your extremities, which is why your fingers and toes may feel cold first.
4. Exposed Skin
Your donation arm is exposed and often resting on a cool armrest. With a needle in your vein and blood flowing through external tubing, heat loss from your arm is increased compared to normal.
5. Individual Factors
- Lower body weight: Smaller donors have less mass to retain heat
- Low body fat: Less insulation means faster heat loss
- Anemia or low iron: Reduced oxygen-carrying capacity affects temperature regulation
- Poor circulation: Some people naturally run cold
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How Cold Will You Get?
The degree of chilliness varies from person to person, but here is what most donors experience:
| Timeframe | What Happens | How It Feels |
|---|---|---|
| First 10-15 min | First 1-2 saline returns | Slight coolness, barely noticeable |
| 15-30 min | 3-4 saline returns | Noticeable chill, especially in fingers and toes |
| 30-60 min | 5-6 saline returns | Feeling cold, possible shivering |
| 60-90 min | Final cycles + prolonged stillness | Full body chill, lips may feel cold |
| After donation | Body rewarming | Warmth returns within 15-30 minutes of moving |
Most donors report that the cold feeling is mild to moderate and goes away quickly after the donation ends and they start moving around. However, some donors — especially those with lower body weight or longer donation times — experience more significant chills.
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Experienced plasma donors have developed many strategies to combat the cold. Here are the most effective:
What to Bring
- A blanket or throw: This is the number one tip from veteran donors. Bring a small fleece blanket to cover your legs and torso
- Warm socks: Your feet get cold first — thick socks make a big difference
- A hoodie or jacket: Wear warm layers you can put on with one hand (your donation arm will be occupied)
- Hand warmers: A disposable hand warmer in your free hand helps
What to Wear
- Layer up: Wear a t-shirt under a hoodie or zip-up jacket
- Long pants: Even in summer, wear full-length pants for donation day
- Warm shoes: Closed-toe shoes with thick socks beat sandals
- Easy arm access: Wear a short-sleeve shirt under your warm layers so staff can access your arm
Ask the Staff
- Warmed saline: Some centers warm their saline to reduce the temperature difference. Ask if this is available
- Heated blankets: Some centers provide warmed blankets on request
- Adjust your chair: Ask to have the donation chair positioned away from air vents
During Donation
- Wiggle your toes: Gentle foot movement generates heat without disturbing the needle
- Squeeze a stress ball: Using your free hand generates warmth and keeps blood flowing
- Drink something warm before: A warm (non-caffeinated) beverage before donation raises your starting temperature
When to Be Concerned
Mild chilliness during plasma donation is completely normal and not dangerous. However, you should alert staff immediately if you experience:
- Uncontrollable shivering that does not stop
- Numbness or tingling in your lips, face, or extremities (may indicate citrate reaction)
- Dizziness or lightheadedness along with cold sensation
- Nausea combined with feeling cold
- Blue lips or fingernails (sign of poor circulation)
These symptoms could indicate a citrate reaction or other issue that requires staff attention. Citrate is the anticoagulant used during donation, and it can temporarily lower blood calcium levels, causing tingling and chills. Staff can slow the return rate or give you calcium supplements (like Tums) to help.
Frequently Asked Questions
Why does plasma donation make me cold but not whole blood donation?
Whole blood donation removes blood and does not return anything to your body. Plasma donation returns red blood cells mixed with room-temperature saline, which actively cools your bloodstream. It is the saline return — not the blood removal — that causes the cold sensation.
Can the center warm the saline before returning it?
Some plasma centers use saline warmers that heat the solution closer to body temperature before returning it. Not all centers have this equipment, but it is worth asking. Warmed saline significantly reduces the cold feeling during donation.
Will I feel cold every time I donate plasma?
Most donors feel some degree of cold during every donation, since the saline is always at room temperature. However, many donors report it becomes less bothersome over time as they learn to dress warmly, bring blankets, and know what to expect.
Is feeling cold during plasma donation dangerous?
Mild chills during donation are completely normal and not dangerous. Your body warms back up within 15-30 minutes after donation. However, if you experience uncontrollable shivering, numbness, tingling, or blue lips, alert staff immediately as these could indicate a citrate reaction.
How long will I feel cold after plasma donation?
Most donors warm up within 15-30 minutes after finishing their donation, especially once they start moving around. Drinking a warm beverage, walking, and putting on warm layers all help speed up the rewarming process. If you still feel cold after an hour, contact the donation center for guidance.