Brief Answer:
Stop using Diltigesic and follow as further advised

Detailed Answer:
Hi.
Thanks for your query, albeit short and specific.
To recapitulate: Male/46 - anal fissure in 2013 - and now - feel like sleeping after applying Diltigesic cream to anal fissure - noted the treatment you are taking after consulting a Doctor.
Diltigesic is known to cause sleep problems, hence stop applying this cream. You can get cured even without that as many other patients do.
Continue Sitz bath: before passing stool as it helps relaxing the muscles which is why Diltigesic is prescribed for. After passing stool, clean with warm water and once in the evening after work.
Continue Flagyl and painkiller.
I hope you are taking laxatives/stool softeners, if not get started on the products which you had used in past and suited you the best.
High fiber diet.
Relaxation- avoid stress and/or anxiety.
Avoid foods and beverages that instigate or enhance the problems.

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

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Brief Answer:
As detailed below.

Detailed Answer:
Ideally saying, it should not as it causes vasodilatation but any given medicines can cause varied side effects sometimes very subjective and rare.
But fissure in ano itself can cause temporary ED due to pain and loss of interest or anxiety of performance.

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