Donating blood: it’s that easy to save lives

Many people rely on blood from donors daily. It is urgently needed for various conditions and after accidents. There are different types of blood donation. How do they differ? And who can actually donate blood? What are the potential risks and side effects?

At a glance

  • Those who donate blood help people in dire need of the blood due to an illness or an accident.
  • As well as donating whole blood, it is also possible to donate only specific blood components, for example plasma or platelets.
  • Healthy adults who weigh more than 50 kilograms are generally eligible to donate.
  • Potential donors are examined before each blood draw.
  • To stop them from feeling faint during or after donating blood, people should have enough to eat and drink beforehand.
  • Donors can also benefit from donating blood.
Member of medical staff smiling and looking after a blood donor who is sitting on a treatment chair.

Why is donating blood important?

Those who donate blood help people with various illnesses, after accidents and during operations. The most common illnesses where donated blood or blood components are needed include cancer and heart and gastrointestinal disorders. In Germany, around 15,000 blood donations are needed daily.

Human blood components cannot be artificially produced. This means the recipients are dependent on the donations. Donor blood enables for instance surgery, blood transfusions after serious accidents and production of vital medicines. 

What are the types of blood donation?

The four most common types of blood donation are whole blood, plasma, platelet and autologous blood donations. 

Whole blood donation

Whole blood donation is the most common type of blood donation. This involves half a liter of blood being collected from a vein in the arm. The blood is divided into its various components after being withdrawn. This means that patients can receive the specific blood components that they need.

The blood collection takes about 5 to 10 minutes. The person should allow around one hour for the entire appointment, including examination, rest time and snack. A whole blood donation can be done roughly every 3 months for women and roughly every 2 months for men – up to an annual maximum of 4 whole blood donations for women and 6 whole blood donations for men. In the meantime the body can compensate again for the loss of blood and iron. 

Important: Since women lose blood and therefore iron during menstruation, whole blood donations are limited to a maximum of 4 a year for them. This stops them losing too much iron. 

Plasma donation

Plasma donation involves the plasma being separated from the rest of the blood and removed. The remaining blood components are fed back into the body. This means that people can donate plasma more often than whole blood. People should allow 1.5 to 2 hours for the entire appointment. Donating plasma takes longer than whole blood as it takes more time to separate the blood components.

Blood plasma consists of 90 percent water, but contains many important substances of the blood. These include proteins that play a role for the immune system and in blood clotting, among other things. These substances are used in particular to produce drugs that help with life-threatening immune disorders or blood clotting disorders.

Thrombocytes donation

To many people, thrombocytes are better known as “platelets”. They are especially needed by the body for blood clotting. People with cancer often do not form any platelets anymore. Administering platelets after major blood loss, for example after an accident or surgery can also be vital.

Platelets can only be used for 4 days after being donated. Also, since only platelets with the matching blood group – and in some cases the matching HLA characteristics – are suitable, donors with the appropriate characteristics are often contacted if necessary. 

Interesting fact: HLA stands for human leukocyte antigen. Based on the HLA characteristics, the immune system decides whether it accepts cells and tissues or rejects them as “foreign”.

Donating platelets follows a similar procedure to the one followed for donating plasma. The whole appointment lasts around 1.5 to 2 hours.

Autologous donation

Some operations involve such a huge loss of blood that a blood transfusion is needed. The blood for the transfusion can be made available through an autologous donation. This involves taking blood from the patient about 5 to 7 weeks before the surgery date and storing it for the operation. 

Your doctor will discuss with you the decision on whether the blood for an operation will come from an autologous donation. It requires a good state of health and sufficient time between the autologous donation and the planned surgical procedure.

Who is allowed to donate blood?

People do not have to meet many requirements to donate blood. Anyone who feels healthy, is at least 18 years old and weighs more than 50 kilos will usually be eligible for blood donation.

Anyone who feels healthy, is at least 18 years old and weighs more than 50 kilos will usually be eligible for blood donation.

If there is any suspicion that the blood from donors may be infectious or might not be good quality, it may be held back (deferred). This means that a potential donor has to wait. The reasons for this could be a possible infection, an operation, risky sexual behavior or poor health. In these cases, a certain amount of time must pass between a (possible) infection or an event and the blood donation. A further reason for a deferral, i.e. a period of waiting until the donation, is a hemoglobin level that is too low before donating the blood.

Examples of infections and events and the appropriate deferral periods (in brackets) are:

People with certain conditions are not allowed to donate blood. These include:

  • severe cardiovascular diseases
  • severe central nervous system disorders
  • some blood clotting disorders
  • chronic illnesses affecting the kidneys, lungs or the digestive system
  • serious disorders of the immune system or metabolism
  • malignant tumors
  • diabetes mellitus, if treated with insulin
  • HIV
  • syphilis

People who consume drugs or misuse medication are also not allowed to donate blood. 

How does donating blood work?

Preparing to donate

Before you donate blood, you need to have enough to eat and drink to strengthen the body. It is especially important to drink a bit more than usual, but no alcoholic drinks. No fatty foods should be eaten either. To donate blood, the person must bring a valid original ID. Your personal data will be recorded when you register.

Questionnaire and examination

Once you have registered you will be asked to fill in a donor questionnaire. This will ask you to provide detailed information about your health. This information will help to establish whether you are eligible to donate blood or plasma.

Then a small drop of blood is taken from your fingertip or earlobe. This determines the hemoglobin level. Hemoglobin is needed in the body to transport oxygen and rebuild red blood cells. The hemoglobin level must be high enough for the blood to be able to transport enough oxygen to the organs during and also after the donation of blood.

You will then be examined by a doctor. This will involve them measuring blood pressure, heart rate and body temperature. A doctor will discuss the questionnaire with you and tell you whether you’re allowed to donate blood.

With a confidential self-deferral, you can decide immediately before donating whether the blood or plasma can be passed on at a later date.


A whole blood donation involves approximately half a liter of blood being taken from the crook of the arm. This only takes about 5 to 10 minutes. Other types of donation (plasma, platelets) involve a cell separator or a plasmapheresis machine separating certain blood components from the rest of the blood and collecting them. The remaining blood components are then re-introduced back into the body. This takes 30-90 minutes. Sterile disposable materials are used for all types of blood donation. Doing it this way avoids infection.

Bei allen Arten von Blutspenden wird steriles Einwegmaterial verwendet. Daher ist eine Infektion auf diesem Wege ausgeschlossen.

What to do after you have donated

After you have donated, you should rest for at least half an hour and have something to eat and drink. Don’t get up until you feel able to. Take it easy for the rest of the day. Do not do anything that could put you or others in danger if you suddenly felt faint. 

Good to know: You will usually receive some food for the day at the end. Some blood donation centers will also give you an expense allowance.

What happens to the donated blood?

A small amount of the blood is taken into tubes. This blood is examined in the laboratory for HIV and other disease pathogens. The blood group and the rhesus factor are also determined.

If the blood is free from pathogens, it is prepared for a possible transfusion at a later date. For this, it is centrifuged. In this process the blood is divided into its individual components – plasma, platelets (thrombocytes), red blood cells (erythrocytes) and white blood cells (leukocytes).

Using the blood plasma

The plasma is deep frozen at minus 30 to minus 40 degrees Celsius. Part of the plasma is used to obtain important components in concentrated form from it, for example, antibodies or clotting factors. Part of the plasma is used as therapeutic plasma as it was obtained from the donors. 

Using the platelets

Platelets are important for blood clotting. They are therefore needed after accidents or during surgery to stop the bleeding. Patients with illnesses that impair the formation of their body’s own platelets are also dependent on platelets. The platelet preparations must be kept moving after being withdrawn to prevent from clotting, and used within 4 days.

Using the red blood cells

The red blood cells (erythrocytes) are needed when a lot of blood is lost, i.e. after serious accidents or during major surgery. Donated red blood cells are also needed with illnesses that result in impairment of the body’s own formation of red blood cells or a loss of red blood cells. The red blood cells are usually made stable by adding stabilizers and kept cool.

Using the white blood cells

The few white blood cells that only make up around 2 percent of the whole blood are removed from the units of stored blood. Therapeutic use of white blood cells requires fairly large amounts, obtained through a different procedure known as apheresis (blood purification).

Are there risks or side effects when donating blood?

The donor may feel faint during and after donating blood if for example their blood pressure decreases. This can range from mild dizziness to loss of consciousness. However, serious problems such as fainting are rare.

Important: Feeling faint occurs less often if the donor has enough to drink before donating blood. This slightly increases the blood volume and the body can better compensate for the losses. If you get dizzy, wait for it to pass and only then get up.

In some cases, the donor may feel sick, but very rarely vomits. They may also experience pain and bruising at the puncture site and local inflammation. Skin nerves at the puncture site are sometimes damaged but this is extremely rare. Long-lasting or persistent impairments are very rare, but cannot be 100% ruled out. 

With a plasma donation, the person can also have a slight tingling of the fingers, the tongue, the mouth or the toes. This is due to the fact that the donor is administered a small amount of an anticoagulant, which can cause tingling.

How do people benefit from donating blood?

Those who regularly donate blood can also have their own health checked regularly since every time they donate the doctor checks whether their blood pressure and their hemoglobin levels are okay. Their body temperature is also measured and their blood analyzed for certain disease pathogens. This identifies whether there is an infection, even if there are not yet any symptoms.

Blood donors receive a blood donor pass. This helps them to find out their own blood group and rhesus factor. This can be beneficial in the event of an accident or emergency surgery.

Finally, many donors report a feeling of elation after donating, also called “warm glow”. This feeling arises from the knowledge that they have done something good, even vital, for another person.

Further information

It is possible to donate blood in some university hospitals and general hospitals and in various blood donation centers. You can find a blood donation center in your vicinity via a search at the Federal Center for Health Education (Bundeszentrale für gesundheitliche Aufklärung).

Reviewed by the German Society for Transfusion Medicine and Immunohematology (Deutsche Gesellschaft für Transfusionsmedizin und Immunhämatologie e.V. – DGTI).

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