Fatigue

• One of the most predominant warning signs of anemia is fatigue. This is a result of a change in the amount of red blood cells in the body. When there is a decrease in the number of red blood cells, the organs become deprived of the oxygen needed to function at an optimal level, which results in fatigue.
  
  

Change in Coloring

• Many times, a person suffering from anemia will begin to appear paler than normal. Again, this is a consequence in the decrease of red blood cells in the body. Usually, a person's coloring will go back to "normal" when the condition is treated.
  
  

Cramping

• While most people associate leg cramps with a need for more potassium in the diet, it can also be a sign of anemia. However, just having some cramping in the legs isn't necessarily a sign of anemia. It will usually be in combination with other symptoms.
  
  

Cardiovascular Changes

• Some people who are suffering from anemia may begin to encounter a change in their heart rates. This is typically seen during times of physical exertion, exhibiting as a more heightened or rapid rate in the beating of the heart.
  
  

Respiratory Changes

• With the change in the level of oxygen in the blood, it shouldn't come as much of a surprise that a person suffering from anemia may encounter a change in their respiration. This particular warning sign usually presents itself as a shortness of breath or a difficulty in catching one's breath during physical activities.
  
  

Focus

• Another fairly common warning sign of anemia is an overall lack of concentration. It could be at work, school or any other activity. Much like the other signs, it revolves around the change in oxygen transported throughout the body.
  
  

Other Warning Signs

• From time to time, a person suffering from anemia may feel a certain sense of lightheadedness or an almost dizziness. This can happen at times of rest or activity, and will usually be accompanied by other symptoms. A number of people suffering from anemia also see changes in their sleep cycles. This may come about as insomnia, which would be a difficulty getting to sleep or stay asleep, or may simply be a restlessness that prohibits a good night's rest.