Is it permissible to wear tight-fitting (ordinary) underwear beneath the Ihram garment to prevent urine leakage resulting from a medical condition, and if not, what is the alternative solution?

Scholars differed concerning the ruling on wearing the tibban (underwear) for a person in a state of ihram. Some held that it is permissible absolutely, while the majority held that it is forbidden, analogizing it to trousers, and some even considered it more deserving of prohibition.

The correct view is that a person in a state of ihram is forbidden from wearing the tibban. The narrations reported from Aisha and Ammar ibn Yasir (may Allah be pleased with them both) regarding its permissibility are to be understood as applying to cases of necessity, such as when exposed awrahs needed to be covered or to alleviate pain resulting from certain ailments.

It is permissible to wear the tibban in cases of necessity, such as for someone working in loading and unloading who fears exposure of their awrah, or someone suffering from skin chafing, a wound in the awrah, or urinary incontinence, with the obligation of offering a fidyah (expiation) in these cases. The fidyah is: feeding six needy persons, or fasting three days, or sacrificing a sheep.