How Much Blood Can You Safely Lose Before the Symptoms Hit?

Nosebleed, period, knife cut – there are so many ways to interrupt a smooth flow of blood and allow it to leave the body. Bleeding happens often and to everyone. You can’t be careful all the time and sometimes you just can’t prevent it.

Most of the time, the body compensates for the loss. However the problem might sometimes be bigger. Movies and TV shows often depict people who are in life danger because of a serious blood loss.

Losing a lot of blood can impact your cardiovascular system in many ways, but how much blood can you safely lose? This article will discuss the importance of blood and explain when a blood loss can be life-threatening.

How Important Is Blood?

Blood is the most important bodily fluid. It circulates through our body thanks to the cardiovascular system. It is a highway that transfers all the important particles to the cells throughout the body.

While it travels, it circulates red blood cells, white blood cells, and platelets. The red blood cells distribute oxygen and the white blood cells defend the body against infections. Platelets play a role in clotting and help stop the bleeding by forming clots on the surface of the wound.

Blood also carries nutrients that feed the cells. It takes away the wasteful substances from the cells and transports chemicals and hormones around. In doing so, blood plays a part in many essential processes in our body.

Closed blood vessels keep the blood contained. When they rupture, some blood will deviate from the original route and spill out. This can happen internally (inside of your body) or externally (out of your body). The technical term for blood loss is hemorrhage.

How Much Blood Do We Have?

The amount of blood people have varies based on the following factors:

  • Age: Children and old-aged people usually have less blood than adults.
  • Sex: Statistically, men have more blood than women.
  • Location: Depending on where you live, you can have more or less blood. For example, people that live on higher altitudes may have more blood than people living in lower. The higher places lack oxygen, so sometimes more blood is needed to get the oxygen to the lungs.
  • Blood disorders: Sometimes we can have fewer blood components in our cardiovascular system because of illnesses or other conditions. The most common conditions include anemia (lack of red blood cells), leukopenia (lack of white blood cells), and thrombocytopenia (lack of platelets).

Scientists say that blood accounts for about 7% of your body weight. This means that a person weighing 180 pounds (80kg) has around 5 liters (1.5 gallons) of blood. A child weighting 80 pounds will have around half of that amount.

How Much Blood Can You Safely Lose?

When you start losing blood, your platelets will try to form a clot to stop the blood from leaving the vessel. If the cut is minor, the bleeding will stop by itself. You will not lose a lot of blood and there will be no consequences on the body. However, sometimes the resulting blood loss can be severe.

There are four stages of blood loss that can affect you differently.

Class One – No Consequences

Class one hemorrhage results in a loss of up to 15 percent of your blood in a short time span. This can happen if you have a moderately serious injury and can’t stop the bleeding right away. When you donate blood, you also lose around 10 percent.

You should not feel any symptoms of blood loss, although some people can feel a little dizzy.

Class Two – Traumatic Reactions

Class two hemorrhage is where the first real symptoms start to appear. This happens when the hemorrhage is between 15 to 30 percent. The body will try to make up for the blood loss by pumping blood more quickly and trying to get all the important particles to your cells.

This triggers traumatic reactions and causes a state of hemorrhagic shock.

You may feel:

  • Increased heart rate
  • Nausea and dizziness
  • Heavy breathing
  • Paleness
  • Anxiety
  • Weakness
  • Cold

Class Three – Passing Out

Once the hemorrhage goes over 30 percent, the body may not be able to compensate for the loss and maintain circulation.

There is a chance that you could pass out. At this stage, blood transfusion will probably be necessary. That is usually the only way your body can set up and maintain a proper cardiovascular flow.

Class Four – Comatose State

When the blood loss becomes greater than 40 percent, the body will not be able to compensate. The heart can’t maintain optimal blood pressure and without blood, the organs will start to fall. Once this happens, you will slip into a coma.

This condition requires medical attention as quickly as possible and even then, the outcome is not always positive. Sometimes the blood loss can be so severe that the body can’t recover. In this instance, even a transfusion might not help.

Seeing a Doctor

If you experience any type of hemorrhage that doesn’t stop or gets worse, you may have to call an ambulance. If you notice any symptoms of internal bleeding (e.g. dark blood in stool, vomiting blood, or coughing blood), you should contact your healthcare provider right away.

If you are wounded and are experiencing heavy bleeding, make sure to apply as much pressure to the wound as you can. Also, elevate the wound above the level of the heart. The body tries to get as much blood as possible to the brain and vital organs, so the pressure and elevation will help your vitals stay active.

So, When Is Blood Loss Safe?

Losing some blood is sometimes inevitable, but there usually aren’t reasons to worry. You can experience hemorrhage in the following situations:

  • Nosebleed
  • Impact injuries
  • Bleeding hemorrhoid
  • A miscarriage
  • Menstruation
  • Childbirth
  • Surgery
  • Blood donation
  • Cuts and animal bites
  • Dental interventions
  • Medical testing

All of these should not cause blood loss of more than 10 percent. This means that you will not feel any symptoms. Your body will do its best to recover the loss in a short time.

So, how much blood can you safely lose? The answer is – a blood loss of up to 15 percent shouldn’t cause any major symptoms. If you lose between 15 and 30 percent, the problem gets more serious. It is never safe to lose more than 30 percent of blood because it seriously affects your body’s inner workings and can have fatal consequences.

Everyday hemorrhages are usually not serious as the body is well-prepared to deal with them. If things get serious, you should call your doctor.