Sorry to pop your Capsules, but....
Applies to omega-3 polyunsaturated fatty acids: oral capsule liquid filled
In addition to its needed effects, some unwanted effects may be caused by omega-3 polyunsaturated fatty acids (the active ingredient contained in Fish Oil). In the eventthat any of these side effects do occur, they may require medical attention.
You should check with your doctor immediately if any of these side effects occur when taking omega-3 polyunsaturated fatty acids:
Incidence not known
Bleeding gums
cough
coughing up blood
difficulty with breathing or swallowing
dizziness
fast or irregular heartbeat
headache
hives, itching, or skin rash
increased menstrual flow or vaginal bleeding
nosebleeds
paralysis
prolonged bleeding from cuts
puffiness or swelling of the eyelids or around the eyes, face, lips, or tongue
red or black, tarry stools
red or dark brown urine
sweating
tightness in the chest
unusual tiredness or weakness
Some of the side effects that can occur with omega-3 polyunsaturated fatty acids may not need medical attention. As your body adjusts to the medicine during treatment these side effects may go away. Your health care professional may also be able to tell you about ways to reduce or prevent some of these side effects. If any of the following side effects continue, are bothersome or if you have any questions about them, check with your health care professional:
Less common
Acid or sour stomach
bad, unusual, or unpleasant (after) taste
belching
bloated or full feeling
change in taste
excess air or gas in the stomach
heartburn
indigestion
stomach discomfort, upset, or pain
Incidence not known
Diarrhea
difficulty having a bowel movement (stool)
loss of appetite
nausea or vomiting
passing of gas
stomach fullness
http://www.drugs.com/sfx/fish-oil-side-effects.html