Q. If one has digestive problems and resulting inflammation that is debilitating, and (during the seder) it affects the ability to serve the meal to the rest of the family and guests, does one have to eat the full shiur of matza each time during the seder to fulfill the mitzva?
A. On a similar question 2124 we wrote: “Normally Poskim recommend for matza are at least approximately 27 or 28 cubic centimeters according to Rav Chaim Noeh. (Shiurei Torah p. 191, 193. However, 28.8 cubic centimeters is mentioned preferable. About 13.5 – 15 gm.). According to Horav Moshe Feinstein zt’l the amount is 44.3 cubic centimeters. (Kol Dodi, p. 60).
In regards to an elderly or ill individual, Horav Shlomo Miller’s opinion recommends half an ounce or 14.8 c.c. or about 14.2 gm.
The Rov added that if the matza is to be dampened with water to make it softer and more digestible, it should maintain its tzuras hapas or basic form and structure.”
In your case you may use the smaller shiur of dampened matza. If possible two kezaisim for Motzi Matza and one for Afikomem. If not at least one for Motzi Matza.
See also question 2137 regarding one who is lo alenu sick with a digestive system disease, and often gets nauseous, or in need to vomit and finds it hard to eat. If he eats a kezais of matza at that time, he may not comply with the mitzva, as is it maybe seen as eating an achila gassa or overeating a meal. He may need to wait until better and repeat.
We answered that if following the above advise does not help much, Horav Shlomo Miller’s Shlit’a opinion is that if the patient was still able to swallow the matza even when nauseous, he complies after the fact in a case of need.
Rabbi A. Bartfeld as advised by Horav Shlomo Miller and Horav Aharon Miller Shlit’a