It is difficult to decide where to start in discussing the many issues affecting fecal incontinence. However, I will lead off with one that has been mentioned previously in the other forums, so there is some known interest. As several members of our group are known to use these products we should have a good exchange of information.
Many of us with fecal incontinence are concerned about personal odor, particularly in a close social situation. One option is to use an internal deodorant. These are FDA-approved tablets usually of either bismuth subgallate (such as Devrom brand) or chlorophyllin-copper (such as Nullo brand). They will not completely eliminate fecal odor, but they will markedly reduce it. If one product does not work for you, try the other as the results vary markedly because of differences in personal body chemistry, diet, and dosage.
Prior to a month-long vacation with foreign travel, plus a cruise, I was concerned about the possibly having a fecal “accident” during an extended shore excursion and then, without having an opportunity to change my diaper, having to return to the ship in close proximity to other people aboard a shuttle bus or ship’s tender. Accordingly, I decided to test some of the internal deodorant products.
The three major categories of internal deodorizers use bismuth subgallate, activated charcoal, or chlorophyl copper compound. Using the same product, some individuals reported eliminating as much as 98% of odor in stool while others reported unsatisfactory results. Although there are numerous name brands, users did not report significant differences by brand. A negative aspect to all three categories is that the products cause constipation to varying degrees.
Based on written reviews, I tried the two most recommended products: bismuth subgallate (Devron brand) and chlorophyl copper compound (Nullo brand).
Devron (bismuth subgallate) - The standard dosage is 6-8 capsules per day. To achieve the desired results I had to take the maximum recommended 8 capsules per day. That is a lot of capsules and causes the use of Devron to be more expensive than chlorophyl copper compound. Taking that many tablets a day also proved to be an inconvenience.
Devron eliminated an estimated 50-70% of odor from my stool as perceived while wearing a “messy” adult diaper. Devron also was slightly constipating (the effects were countered by my use of daily enemas and Miralax). At the practical level, when wearing a messy diaper, Devron was helpful in reducing fecal odor. I felt that in an open environment I could walk near to another person without them noticing. I would not however feel comfortable sharing a small space, such as a stairway or elevator, for any length of time. Bismuth subgallate has the advantage of being relatively quick-acting. I noticed a substantial reduction of odor in four days. Bismuth subgallate will turn the stool black.Nullo (chlorophyl copper compound) - The standard recommended dosage is two capsules per day, with a maximum of three. Two capsules eliminated an estimated 80% of stool odor as perceived while wearing a messy diaper. The highest recommended dosage of three capsules per day eliminated an estimated 85-90% of odor from stool. For me, Nullo was markedly more constipating than Devron. Despite my use of daily enemas and Miralax, the combined constipating effects of the Nullo with my pain medicines was so much that I had to reduce my dosage of Nullo to two capsules per day.
When wearing a messy diaper Nullo was very effective in eliminating most fecal odor - on several occasions my wife was not aware that I had messed my diaper. On more than one occasion, when she knew that I had experienced an accident, she stood two feet away and commented that there was no odor 
. While using Nullo I probably briefly could share an elevator with someone or sit two seats away from someone for a brief period of time without them noticing. However, my wife, sitting next to me, probably would. Nullo takes 2-14 days to reach maximum effectiveness. I noticed an improvement in stool odor in four days and a marked reduction in odor in 12 days. Chlorophyl copper compound will turn the stool an unpleasant green. Soiling your underwear or outer clothing with feces may leave green stains similar to grass stains, which are difficult or impossible to remove.Due to insufficient time before my trip, I did not test activated charcoal. I have read that it helps, but not so effectively as Nullo or Devrom.
I would recommend that others first test chlorophyl copper compound (Nullo), then bismuth subgallate (Devron), and finally activated charcoal, in that order.
Nota bene: despite the use of internal deodorants, effective diapering techniques by the user are critical to successful fecal odor control. This includes 1) wearing a plastic-backed diaper, plus 2) wearing a vinyl plastic diaper cover or “plastic pants” on top to contain both diaper leaks and odor. PUL or polyurethene laminate breathable diaper covers were less effective for odor control than vinyl plastic covers. Traditional plastic pants, while warmer to wear, are more effective in containing odor than breathable materials. 3) It also is essential that the diaper itself properly fit the user’s anatomy and be snugly taped so as to reduce any gaps at the legs (the source of most fecal leaks). Not everyone does this. Pull-up diapers (absorbent underwear) usually are not adequate for fecal containment as they both leak more than taped diapers and, all being breathable, transmit far more odor.