Donating blood is a simple way for most people to help others in need. However, blood donors will need to take certain precautions after donating to help their body recover. These include not working out directly after donating blood.

After giving blood, it is best to rest for at least the rest of the day.

Working out the same day after giving blood can be harmful and may lead to fainting, among other effects.

a woman relaxing on a couch because it is best to rest rather than workout after giving bloodShare on Pinterest
A person should avoid vigorous exercise directly after giving blood.

The American Red Cross recommend avoiding heavy lifting or vigorous exercise for at least the rest of the day after donating blood. However, according to the World Health Organization (WHO), a person should avoid playing sports or taking part in strenuous activity for 48 hours.

Weightlifting, body exercises, and arm-related exercises, such as tennis, may put extra pressure on the needle site, which could increase the risk of bleeding, bruising, and soreness in the arm.

Both aerobic and anaerobic exercises may also increase the oxygen demands of the body. If a person has just given blood, their body may not be able to keep up with these demands.

The authors of a 2016 review estimate that whole blood donation causes reductions in a person’s overall exercise capacity for about the first 2 days after blood donation.

From there, it is important to build back up to an intense exercise routine gradually. A person should try each new exercise slowly and deliberately to see how it will affect the body. They should also take extra time to rest between sets or workouts.

Every 2 seconds, someone in the United States needs blood, but supplies are low due to COVID-19. To find out more about blood donation and how you can help, please visit our dedicated hub.

Following a blood donation, a person may experience one or more side effects.

Fatigue

Fatigue may occur in anyone who donates blood, especially as the body recovers. A person who regularly works out should not expect to operate at peak performance in the 2 days following blood donation.

Rest is one of the most important factors in battling fatigue. Taking regular and longer break periods may help with fatigue. Working out at a lower capacity than usual may also help prevent or minimize fatigue.

Dehydration

Symptoms such as dark urine, dry mouth, and dizziness may all be signs of dehydration.

A blood donation takes liquid and minerals out of the body. It is important to restore these liquids.

Even before the procedure, most donation centers will advise the person to drink extra water to prepare. After the donation, the center will offer the person fresh juice or water as they recover. The American Red Cross suggest drinking an additional 16 ounces (oz) of water, equivalent to 2 cups, before the appointment.

In the days that follow, liquids are just as important, as they can help prevent dehydration and replenish water and mineral stores in the body.

A good aim is to drink an extra 32 oz of liquids the day after donation. Aside from water, other forms of liquid are important to help provide nutrients and minerals to the body.

People can increase their liquid intake by consuming:

  • broth and soup
  • juice
  • low sugar electrolyte drinks
  • moisture-rich fruits and vegetables, such as melons, cucumbers, and greens

It is also important to avoid alcoholic beverages for at least the first 24 hours.

Avoiding products containing caffeine may also aid recovery. The American Heart Association (AHA) note that caffeine is a diuretic and may actually cause the body to lose more fluids.

Staying hydrated helps the body recover blood stores and may help prevent symptoms.

Iron deficiency

Blood donation also causes a loss of iron-rich hemoglobin in the blood cells. As a result, less oxygen makes it to the muscles.

For this reason, it is important to replenish these iron stores in the days that follow blood donation. The National Institutes of Health (NIH) recommend that all donors add foods rich in iron and vitamin C to their diet following donation.

These foods include:

  • lean meat
  • poultry
  • seafood
  • beans
  • lentils
  • fresh greens, such as spinach
  • tofu
  • iron-fortified cereals

Some people may benefit from also taking an iron supplement each day to ensure that they have enough iron in their system. A healthcare professional can offer advice on whether this is necessary.

Getting enough iron to avoid iron deficiency may also help with other symptoms, such as fatigue.

For athletes or those who place a particularly high value on working out each day, it may also be important to time their blood donation to suit their workout schedule.

It may be best for people to donate at the beginning of a break period or off day. Doing this will give the body time to recover.

Even with this recovery window, it is important to start working out slowly and pay attention to any signs that the body sends during exercise.

If the person becomes heavily fatigued, dizzy, or lightheaded, they should stop their workout to sit or lie down and rest until the feeling passes. People should not attempt to push through these symptoms, as they may lead to loss of balance, falls, or fainting, which can all be especially dangerous while working out.

Donating blood may not be the best idea when a person must perform or compete, as donating can affect a person’s ability to work out, and they will not reach their highest exercise capacity in the days following donation.

Giving blood is a simple way to help others in need. While the process itself carries very little risk for healthy people, donors should limit their physical activity following blood donation.

People should wait at least a full day, preferably 48 hours, before working out and be ready to take regular rest periods.

A person is unlikely to be at full exercise capacity for a few days. While recovering, it is important to drink extra liquids and maintain a healthful diet.