What about my health and past must I disclose before a shidduch, illnesses, medications, circumstances, and where is the limit of what is required?ask your rav

A candidate is not obliged to volunteer everything that might concern someone, but must disclose a serious threat to the couple's future. Under that heading he places conditions that prevent one from being a spouse or a parent, and serious hereditary illnesses; the family should discuss these with a rav in advance. At the same time, one may not lie outright about anything. He distinguishes the candidate's own obligations from the role of the shadchan.

“one may not lie outright about anything”

In his private replies, diabetes must be disclosed before the shidduch is concluded, even if it is controlled with medication; psychiatric medication with side effects must also be reported. In other replies he does not require reporting high blood pressure alone when the person is otherwise healthy, or the medication for concentration named in that question, which in that case did not indicate illness. A small amount of daily work as a sofer is likewise not considered a contradiction of the reputation of someone who learns all day. Carrying these replies over to a different diagnosis or medication requires clarifying the specifics. Serious health problems must be disclosed before the shidduch is concluded. Together with his other replies a clear line emerges: the minor and obvious need not be disclosed, the serious must be, and before the shidduch is concluded, not after.

“this must be revealed before the shidduch is concluded, even though it is controlled through medication”

Here, as in all of a Jew's affairs, one must act according to Jewish law, and he gives the exact order of steps: first clarify all the necessary details with the doctor, the one who treated the person then and is following him now, and then, with that information, turn to a rav who actively issues halachic rulings. In such a matter a person should not decide for himself whether to tell or not.

He offers one litmus test: ask yourself what reaction you can reasonably expect from your spouse when he or she finds this out months or years from now, and whether the very fact of learning it late will hurt. If the likely response is that you hid this all along and how can I trust you now, then it needs to be told in advance. The same question, he stresses, must be asked by shadchanim, advisers and parents before they decide to keep anything back. He extends the principle beyond health: anything that might hinder a person in coping with life, or casts a shadow on his character or livelihood, must be weighed very carefully. And to the question of who decides what counts as minor he answers that there is no general answer: some people are more sensitive, others less; some things are objectively trivial, like not being able to stand chocolate, but people will react very differently to having been held back a year in school.

“What kind of a reaction can I reasonably expect my spouse to have when he or she find this out”