I've been plagued with an anal fissure for over 10 years. I've tried many things, and have finally found a few things that are working for me that I'd like to share.
First of all, I quit drinking coffee. I noticed that I would frequently have bowel movements after drinking it, so decided to try to quit it and see what would happen. I substituted green tea, and was able to avoid any withdrawal headache. I would suggest watching carefully what you intake and how it affects your bowel movements, especially if you have an easily irritable stomach and bowels. With anal fissures, I believe it's important to have regular and healthy bowel movements, that don't require a lot of wiping which will only irritate the fissure more and suppress healing. So watch what irritates it and stop those things or reduce them.
Secondly, when I do have a bowel movement, instead of wiping a lot, I'll only wipe once with toilet paper, then watch thoroughly with soapy water using your hand. I know it's gross, but you need to irritate this area as little as possible. Also, think of it as a cut that needs to heal. What do you do to cuts? You wash them and keep them clean to prevent infection. I think the same applies with fissures. If you can stomach it, use you finger to wash inside, and then to rinse, and gently wipe dry with a paper towel.
Third, I've been applying a solution of pure olive oil (from whole foods) and crushed up MSM tablet, which promotes the healing. You can crush it by putting it in a plastic baggy and pounding with a mallet. You want it in powder form. If it's to chunky it will scratch and only hurt the situation. Mix it thoroughly with the olive oil and apply to the fissure and inside the anus after every bowel movement, when you get up in the morning and before you go to sleep at night.
Finally, itching. An anal fissure can itch terribly, but scratching it will only make it worse. When it itches what keeps me from scratching is to think that when a wound is healing, sometimes it itches, therefore if the fissure is itching it is healing, which is a sign of progress. This thought keeps me from scratching and therefore setting healing back.
I would say that mostly it is about finding out what causes your particular body to have unhealthy bowel movements(really watery or really hard) and substituting something that doesn't have that affect. Coffee, alcohol, greasy and junky foods, etc.
This has been working for me, I hope it helps others as this is a really draining and painful illness to have.