How does utilitarianism regard lying?

If it helps more people to lie than it is O.K. A senior with dementia who keeps asking about visiting a dead relative it might be best to tell them that they are away for a while. No point in re-traumatizing every day.

”... although the widespread practice of lying and stealing would have bad consequences, resulting in a loss of trustworthiness and security, it is not certain that an occasional lie to avoid embarrassment or an occasional theft from a rich man would not have good consequences, and thus be permissible or even required by Utilitarianism. But the Utilitarian readily answers that the widespread practice of such acts would result in a loss of trustworthiness and security. To meet the objection to not permitting an occasional lie or theft, some philosophers have defended a modification labelled “rule” Utilitarianism. It permits a particular act on a particular occasion to be adjudged right or wrong according to whether it is in accordance with or in violation of a useful rule; and a rule is judged useful or not by the consequences of its general practice. Mill has sometimes been interpreted as a “rule” Utilitarian, whereas Bentham and Sidgwick were “act” Utilitarians.”

http://www.utilitarianism.com/utilitarianism.html