Fish Odor

• Taking fish oil supplements can cause the skin, breath and urine to have a fishy smell.
  
  

Pregnancy

• Fish oil is very high in vitamin A, which can cause birth defects. A woman should not take fish oil supplements early in her pregnancy.
  
  

Asthma

• People with asthma may find the condition worsened when taking fish oil supplements.
  
  

Blood

• Fish oil thins the blood, so users may experience occasional nose bleeds and might bruise more easily.
  
  

Gastrointestinal Issues

• Common side effects of fish oil supplements include nausea, diarrhea and excessive gas.
  
  

Serious Reactions

• Fever, flu like symptoms, chest pain and irregular heartbeat are signs of a serious reaction to fish oil supplements. A doctor should be consulted if any of these issues occur after taking fish oil supplements.