Blood washing is an informal term for therapeutic apheresis, a medical procedure that removes specific harmful components from your blood. A machine draws blood from a vein, spins it to separate its parts, filters out the targeted substance (such as plasma containing disease-causing antibodies or excess cholesterol), and returns the remaining blood to your body. The procedure takes one to four hours per session and is used to treat dozens of conditions, from autoimmune diseases to dangerously high cholesterol.
How the Procedure Works
During a session, you’re connected to the apheresis machine through one or two intravenous lines. Blood flows out through one line and into the machine, where it’s separated into layers by rapid spinning (centrifugation) or by passing through a specialized filter membrane. Both methods achieve the same goal: isolating the problem component so it can be removed.
Once the machine pulls out the targeted fraction, everything else, your red blood cells, platelets, and other healthy components, is mixed with replacement fluid and returned to you through the second line. An anticoagulant called citrate keeps the blood from clotting while it’s outside your body. The whole process typically runs between one and four hours, depending on what’s being removed and how much blood needs to be processed.
Types of Blood Washing
The word “apheresis” comes from a Greek term meaning “to take away,” and the procedure branches into two main categories based on what’s being taken.
- Plasmapheresis (plasma exchange): Removes the liquid portion of blood, called plasma, along with the antibodies, immune complexes, or toxic proteins dissolved in it. The plasma is discarded and replaced with a substitute fluid, usually albumin or donor plasma.
- Cytapheresis: Targets specific blood cells rather than plasma. This can mean removing excess white blood cells in certain leukemias, extracting platelets, or collecting stem cells for transplant.
A more specialized form, lipoprotein apheresis, filters out LDL cholesterol from the plasma. It’s used in people with inherited high cholesterol who don’t respond adequately to medications.
Conditions It Treats
The American Society for Apheresis recognizes 84 diseases and conditions with 157 specific treatment indications. The most well-established uses fall into a few categories.
In autoimmune and neurological diseases, plasma exchange physically removes the rogue antibodies attacking the body’s own tissues. Guillain-Barré syndrome, where the immune system damages peripheral nerves and causes rapidly progressing weakness, is one of the best-known indications. Myasthenia gravis, a condition that causes severe muscle fatigue, is another. In both cases, stripping harmful antibodies from the blood can produce noticeable improvement within days.
For people with familial hypercholesterolemia, a genetic condition that drives LDL cholesterol to extreme levels, lipoprotein apheresis can be a lifeline. Candidates generally include those with existing heart disease and LDL above 190 mg/dL, or those without heart disease but with LDL above 250 mg/dL plus a family history of early heart attacks. People with the most severe form, homozygous familial hypercholesterolemia, are recommended for apheresis because cholesterol-lowering drugs alone rarely bring their levels to a safe range.
Other recognized uses include treating thrombotic thrombocytopenic purpura (a dangerous blood-clotting disorder), certain kidney diseases caused by antibody deposits, and complications following organ transplants where the recipient’s immune system produces antibodies against the new organ.
Side Effects and Risks
Most sessions are well tolerated, but the anticoagulant citrate causes the most common side effect: a temporary drop in calcium levels. Citrate binds to calcium in your blood, which can produce tingling around the mouth, light-headedness, shivering, or muscle twitching. These symptoms are usually mild and resolve when the infusion rate is slowed or calcium is supplemented during the session. In rare cases, calcium levels drop far enough to cause muscle spasms or, very rarely, seizures.
Overall adverse event rates are low. In one study of over 3,000 platelet-collection procedures, the total complication rate was 2.7%, with vascular injuries at the needle site (1.6%) and citrate reactions (0.96%) being the most frequent. Fainting or near-fainting episodes occurred in fewer than 1 in 1,000 sessions. Therapeutic plasma exchange carried a citrate reaction rate of about 1.2%. Serious complications like severe allergic reactions or infections from the catheter site are uncommon but possible.
What a Treatment Course Looks Like
A single session isn’t usually enough. Most treatment protocols call for a series of sessions, often five or more, spread over days or weeks depending on the condition. For Guillain-Barré syndrome, a typical course involves five plasma exchanges. For chronic conditions like familial hypercholesterolemia, treatments may continue on a regular schedule, sometimes every one to two weeks, indefinitely.
Each session costs roughly $900 to $1,000 in direct medical expenses, though total charges including facility fees, catheter placement, and replacement fluids vary widely. A five-session course of plasma exchange has been estimated at around $4,600 in direct costs, which is less than half the cost of the alternative treatment (intravenous immunoglobulin) for conditions like Guillain-Barré. Insurance typically covers apheresis when it’s prescribed for an established medical indication, but coverage for off-label uses is far less certain.
Blood Washing for Long COVID
Interest in blood washing surged during the post-COVID era, with some clinics promoting plasmapheresis as a way to remove so-called “microclots” linked to long COVID symptoms. The theory is that abnormal clotting proteins persist in the blood after infection and contribute to fatigue, brain fog, and other lingering problems.
The evidence does not currently support this use. A Cochrane review found no completed or ongoing randomized controlled trials testing plasmapheresis for removing these clotting proteins in people with long COVID. The review concluded that without reliable research showing these particles actually drive the condition, there is no established rationale for the procedure. Clinics offering it outside of a clinical trial setting are getting ahead of the science, and the procedure carries real costs and risks. If you’re considering it for long COVID, know that no major medical guideline recommends it for this purpose.
How It Differs From Dialysis
People sometimes confuse blood washing with kidney dialysis because both involve running blood through a machine. The key difference is what each procedure removes. Dialysis filters out small waste molecules like urea and excess fluid that the kidneys can no longer handle. Apheresis targets much larger molecules: antibodies, immune complexes, lipoproteins, or entire cells. The two procedures use different equipment, treat different conditions, and aren’t interchangeable. Some patients with kidney failure do receive both, but for separate reasons.