Can We Wear Underwear in Ihram?
Question

I am going for Haj this year, I have a medical condition whereby I need to wear tight underwear (normal underwear) to avoid urine drops coming out in movements like in Prayers and staining my outer clothes. Under these conditions is it allowed to wear normal underwear under the Ihram garment? If not, what is the alternative solution?
Praise be to Allah.Wearing underwear in ihram
The scholars differed concerning the ruling on men wearing underwear that covers the most private part of the ‘awrah. Some of them are of the view that it is permissible even in cases other than those of necessity . They said: There is no text that forbids it among the things that the muhrim (pilgrim in ihram) is not allowed to wear. 
But the majority of the scholars are of the view that wearing it is not permissible by analogy with trousers. Some scholars were of the view that it is even more forbidden than trousers. 
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said: 
“Similarly, underwear is more (forbidden) than trousers.” (Majmu’al-Fatawa, 21/206)
Ibn al-Qayyim (may Allah have mercy on him) said: 
Al-Muzni said: 
“The jurists from the time of the Messenger of Allah (peace and blessings of Allah be upon him) until now use analogy to derive rulings on matters of religion.  
He said:  
They unanimously agreed that what appears to be valid on the basis of analogy is valid, and what appears to be invalid on the basis of analogy is invalid, and it is not permissible for anyone to reject analogy, because it is comparing between matters and seeking the similarities between them. 
For example, the Prophet (peace and blessings of Allah be upon him) forbade the pilgrim in ihram to wear a shirt, trousers, head covering and khufuf, and he did not restrict it to these things only, rather the prohibition also applies to cloaks, caps, kufis (white cotton skull caps), socks and underwear, etc.” (I’lam al-Muwaqqi’in, 1/205-207) 
Thus, it is clear that those who regard it as permissible to wear underwear on the basis that it is not mentioned in the hadith in which the Prophet (peace and blessings of Allah be upon him) described what the pilgrim in ihram should not wear, are mistaken. 
Ibn ‘Abd al-Barr (may Allah have mercy on him) said: 
“Under the same heading as the clothes mentioned in this hadith, such as shirts, trousers, skull caps etc, come all kinds of tailored clothes, so it is not permissible for the pilgrim in ihram to wear any of them, according to all of the scholars.” (Al-Tamhid, 15/104) 
Al-Hafiz Ibn Hajar (may Allah have mercy on him) said: 
“‘Iyad said: The Muslims are unanimously agreed that the things mentioned in this hadith cannot be worn by the muhrim , and that the reference to shirts and pants includes all tailored items, and skull caps and turbans include all things that cover the head, whether they are tailored or otherwise, and khufuf refers to everything that covers the foot.”
What is meant by tailored clothes is that which is worn on the place for which it is made, even if it is part of the body.” (Fath al-Bari, 3/402) 
Those who say that it is permissible for the muhrim to wear underwear quoted as evidence the report from ‘Aishah (may Allah be pleased with her) which said that she allowed porters to wear it, and the report that ‘Ammar ibn Yasir used to wear it. 
1. The report of ‘Aishah 
Al-Bukhari (may Allah have mercy on him) said in his Sahih (2/558) Chapter on putting on perfume at the time of entering ihram and what is worn when wanting to enter ihram. 
“‘Aishah (may Allah be pleased with her) did not see anything wrong with wearing underwear for those who were lifting up her howdah (onto the camel).” 
Al-Hafiz Ibn Hajar (may Allah have mercy on him) said: 
“The report of ‘Aishah reached Sa’id ibn Mansur via ‘Abd al-Rahman ibn al-Qasim from his father from ‘Aishah, that she did Hajj with two slaves of hers and when they lifted up (the howdah) something of them would appear, so she told them to put on underwear, and they put it on when they were in ihram. 
This is a refutation of Ibn al-Tin in his saying that ‘Aishah was referring to women, because they are allowed to wear tailored clothes (in ihram), unlike men. It is as if this was the view held by ‘Aishah, otherwise the majority are of the view that there is no difference between underwear and trousers with regard to it being forbidden for the pilgrim in ihram.” (Fath al-Bari, 3/397) 
The answer to this is that ‘Aishah told them to do that as a case of necessity, because their ‘awrah was becoming uncovered; it does not indicate that it is permissible in cases other than necessity. 
2. The report of ‘Ammar 
Ibn Abi Shaybah narrated that Habib ibn Abi Thabit said:  I saw ‘Ammar ibn Yasir wearing an undergarment when he was in ‘Arafah. (Musannaf Ibn Abi Shaybah, 6/34)
This may be understood as being a case of necessity, as there is a report narrated by Ibn Shabbah in Akhbar al-Madinah (3/1100) which indicates that ‘Ammar ibn Yasir (may Allah be pleased with him) was injured at the time of ‘Uthman ibn ‘Affan (may Allah be pleased with him), concerning which he said: “I cannot control my urine.” 
In al-Nihayah fi Gharib al-Athar (2/126) it says: 
“In the hadith of ‘Abd Khayr it says: I saw ‘Ammar wearing an undergarment, and he said: “I have a bladder problem.”  
The undergarment is short pants that cover the private parts only. 
These reports, even though they are ahad reports, still indicate that there is a basis for that. 
The correct view is that the man who is in ihram is not allowed to wear an undergarment, and the report narrated from ‘Aishah may be understood as referring to a case of necessity; it does not suggest that the one who wears it does not have to offer a fidyah (ransom). 
The report from ‘Ammar ibn Yasir may also be understood as referring to a case of necessity, as he was suffering from a bladder problem. 
Shaykh Muhammad al-Amin al-Shanqiti (may Allah have mercy on him) said:  
“From the report of ‘Aishah, it seems that she granted a concession allowing those who were lifting up her hawdah to wear undergarments due to necessity, as their ‘awrahs were becoming uncovered. This indicates that it is not permissible except in cases of necessity. And Allah knows best.” (Adwa al-Bayan, 5/464) 
When wearing underwear in ihram is permissible
It is permissible for one who is working as a porter – for example – and is afraid that his ‘awrah may become uncovered, to wear an undergarment. It is also permissible for one whose skin is broken due to chafing , and he fears that he may be harmed.
It is also permissible for one who has a wound in the ‘awrah area and needs to cover it, and for one who is suffering from incontinence – which is akin to the case of ‘Ammar ibn Yasir. 
 Any expiation for wearing underwear in ihram?
In all of these and similar cases, the one who wears it has to offer a fidyah, which is feeding six poor persons, or fasting for three days, or slaughtering a sheep. 
Allah says (interpretation of the meaning): 
“And whosoever of you is ill or has an ailment in his scalp (necessitating shaving), he must pay a Fidyah (ransom) of either observing Sawm (fasts) (three days) or giving Sadaqah (charity — feeding six poor persons) or offering sacrifice (one sheep).” [al-Baqarah 2:196]
‘Abd-Allah ibn Ma’qil said: I sat with Ka’b ibn ‘Ujrah (may Allah be pleased with him) and asked him about the fidyah. He said: That was revealed concerning me in particular but it applies to all of you. I was brought to the Messenger of Allah (peace and blessings of Allah be upon him) with lice crawling on my face. He said: “I did not think that your problem had become as bad as I see it. Can you afford a sheep?” I said: No. He said: “Then fast for three days, or feed six poor persons, giving each one half a sa’.” (Narrated by al-Bukhari (1721) and Muslim (1201) 
Shaykh Muhammad ibn Salih al-‘Uthaymin was asked about a pilgrim in ihram wearing an undergarment, because if he does not wear it he will suffer some harm. 
He replied: 
“If he is afraid that he may suffer some harm, there is nothing wrong with him wearing it, but if he can feed six poor persons, giving each one half a sa’, that is better.” (Liqa-at al-Bab il-Maftuh, 177/question no. 16) 
Please see also the answers to questions no. 20870  and 49033 . 
And Allah knows best.