Brief Answer:
As detailed below.

Detailed Answer:
Hi.
Thanks for your query.
To recapitulate: Male/31 - fissure in ano 3+ years - hard stools cause it - heals and does not recur if Miralax is taken - Colace (docusate sodium) a stool softener
does not help -

To answer your queries:
- What would cause this?
> Your intestines have got adjusted to Miralax which contains polyethylene glycol 3350 hence once you stop it you get hard stools and the fissure as a result of hard stools causing the anal skin to tear to cause the fissure.

- Was my body addicted to Miralax.
> You can say dependent. Yes your intestines have got adjusted to Miralax to have proper functioning.

- I am only 31 years old so don't want to be dependent on a product to poop, but need to heal this fissure.
> Fissure is a small cut on the skin of the anal verge, which gets a tear due to hard stool passing over it. Since this is a chronic anal fissure the added factors are the scar that develop over the fissure might be thin and easily amenable to ear and tear. Another factor is the spam or fibrosis of the internal anal sphincter not allowing it to open fully. Hence the surgery of anal dilatation or internal sphincterotomy may help you to get a cure.

-Is Miralax safe to take for 4 months or so?
> This question has its fallacies. Since you need it to relieve of the problems, you have to take it till you are getting other modes of management of the fissure that you have over 3 years.
Is may not be sage to take it for long duration.

-Can you just stop it or do you have to wean off?
> No, you can not just stop it as per the history you already have provided.
You need an effective alternate and additional modes under the care of a General Surgeon and need to go for some procedure as detailed above as per the choice of your General Surgeon or Proctologist on clinical evaluation, examination.

I hope this answers your query.
Please feel free to ask for further relevant queries if you feel that there is a gap of communication.

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