Quite a number of people with constipation issue got diarrhea after taking coconut oil on an empty stomach. From this we can see that coconut oil does help with constipation. However, you don't have to go through that exhausting diarrhea in order to relieve constipation with coconut oil.
All you need to do is eat coconut oil with or after food. Avoid consuming coconut oil by itself when your stomach is empty. An empty stomach will make coconut oil digest faster. Quick digestion means that coconut oil's laxative effect will kick in faster and stronger.
How about rubbing coconut oil on stomach, can it help with constipation?
Some people say that coconut oil may enter through the skin to stimulate bowel movement. If you do feel that rubbing coconut oil on stomach can help with constipation, that's probably due to you feeling relaxed on massaging your tummy. Not because of coconut oil.
Our skin will absorb coconut oil for its own use for the most part. Even when you put a lot (like one tablespoon) of coconut oil on your stomach, I'm afraid very little will go inside your body to move your bowels.
That said, the best way to help with constipation or even prevent it is to ingest coconut oil.