Dr. Michael Zhihua Li M.D.

What does a black stool indicate?A black or dark red-colored stool is called tarry or bloody stools. However, passing dark-colored stools is not always caused by serious problems. One of the most common causes of black stools is the consumption of iron supplements, particularly in people who have...

A dark stool refers to a stool that is either black or dark red in color. You may pass dark bowel movements after consuming dark-colored foods or when an injury or bleeding is present in your gastrointestinal tract. If you pass dark or bloody stools, see your doctor immediately to rule out serious...

A pain that may start or spread from anywhere in between the chest to the pelvic region is often referred to as abdominal pain. Abdominal pain is of different types. Some of them are acute, while others are chronic. Some of them may be rated as mild, while others may range between moderate and...

Fatigue is the feeling of exhaustion when you lack adequate energy and strength to continue with the work. In most cases, the person with fatigue feels like taking rest due to the lack of energy. This is different from the general weakness wherein the person lacks enough muscle and physical...

What is yawning?Usually, yawning is associated with boredom, fatigue, and tiredness. Yawning is also very common in animals, such as dogs, monkeys, snakes, and carnivores. Yawning is also associated with numerous superstitious beliefs.In humans, yawning is considered as a purposeful non-verbal...

IntroductionCyanosis is the medical term for a bluish discoloration of the skin, nails, toes, and mucous membranes. It is generally caused by low levels of oxygen in the blood. Normally, blood appears bright red when it is fully oxygenated. However, when blood does not have enough oxygen, it turns...