I was diagnosed with an anal fissure a few weeks ago and am using a prescription cream of lidocaine and nifedipine. I've had IBS-C for years and never had a fissure before, and I don't think it's a coincidence that it developed after I started taking Linzess a few months ago. I'm on the highest dose (290 mcg) but unlike when I was on the lowest dose several years ago and had what I called "borderline diarrhea" almost every day, the drug now is unpredictable. I have days with no activity and days with a lot, sometimes very hard, large stools that probably caused the fissure and now are interfering with healing. I'd like to try something to make the stools a little softer and easier to pass. My doctor suggested lactulose, which I tried a few years ago and recall that it did little or nothing despite assurances that it would have a very strong effect. I told the doctor I"d like to try magnesium. My magnesium level was tested recently and is normal, so I guess I wouldn't need a high dose. He suggested a product, which I didn't see the first time I browsed in a store, but will continue to look for. In general, what type of magnesium should I try, and what's an entry level dose? I'd like to try something that I can adjust, like a liquid, rather than a tablet with a fixed dose that might be too much.