Even in Ashkenaz it was clear that the custom to refrain from kitniyot is not as severe as eating ḥametz. Therefore, under pressing circumstances like drought or famine, leading halakhic authorities permitted eating kitniyot. In actuality, rabbis have often disagreed whether the need was pressing enough to permit eating kitniyot. Some rabbis were inclined to be lenient, others to be stringent, and still others to permit kitniyot to the poor alone, requiring the wealthy to buy other types of foods. On such matters, one must follow the ruling of the accepted local rabbinic authorities.
Some Aḥaronim write that when applying these leniencies to kitniyot, it is better first to permit kitniyot that do not resemble cereal grain, and only permit rice, millet, and buckwheat when there is no choice (Nishmat Adam). Additionally, several Aḥaronim state that when applying these leniencies, one should first scald the kitniyot in boiling water, since scalding prevents even cereal grains from becoming ḥametz. Even though in practice we do not permit scalding cereal grains on Pesaḥ (see above, 2:7), when it is necessary to be lenient with kitniyot, it is best to take precautions to the degree possible (Ḥatam Sofer OḤ §122; MB 453:7).
One who is ill and needs to eat kitniyot may do so, even if he is not dangerously ill. For example, someone suffering from constipation may swallow flaxseed with water as a laxative. One may likewise feed kitniyot dishes to children who need it (Ḥayei Adam 127:6), though it is proper to set aside special kelim for this. Anytime one acts leniently, the kitniyot should be thoroughly inspected to ensure that they contain no cereal grains.