What's the alternative to purify after intercourse?

You don't have to ghusl there is tayammum in Islam which can be a alternative to ghusl.It will make you pure and you can pray again.

Reference https://islamqa.info/en/answers/40204/it-is-permissible-to-remove-janaabah-by-means-of-tayammum-when-there-is-an-excuse-for-that

This might need some elaboration (that i hopefully will add later), but

You should know that the rulings of Islam are made in such way that they shouldn't harm people or cause them death.

• Allah does not charge a soul except [with that within] its capacity. ... (2.286)
• So fear Allah as much as you are able and listen and obey and spend [in the way of Allah ]; it is better for your selves. And whoever is protected from the stinginess of his soul - it is those who will be the successful. (64:16)

So in case of necessity and danger for life there one shouldn't harm oneself if what Allah ordered for a regular case would do so.

Further the ruling for a person who had intercourse or other causes of semen emission like a wet dream is to perform ghusl as Allah says:

... And if you are in a state of janabah, then purify yourselves. But if you are ill or on a journey or one of you comes from the place of relieving himself or you have contacted women and do not find water, then seek clean earth and wipe over your faces and hands with it. ... (5:6)

If ghusl would cause your death you may deviate from it to some extent, based on the alternatives offered by shar'ia and ijtihad of scholars. One must therefore check whether Tayyamum is an option. Beside the verse quoted above we may find support in the following hadith as a possible evidence.

Generally scholars offer the following solutions:

• performing ghusl in a "light" manner:
  • by washing body parts that can be washed without the risk of causing harm or dead and performing mash (wiping) on the other body parts.
  • other say you should wash the body parts that can be washed and perform tayammum for the rest (wiping other body parts is not allowed).
  • again other say you perform ghusl for the body parts you can wash and neither perform tayammum nor wiping for the others.

And finally there's a more or less reconciliation of the above views: perform ghusl for those part you can safely pour water on, perform wiping for those parts you can safely touch with humid hands and tayyamum for the rest. (See also fatwa #115376 on islamweb).

Be aware that if ghusl can be performed safely if you toke certain precautions you should perform it (fully) and only deviate from it if there is a real risk for your life.

Two diffeernt statements on islamqa

The following quote form islamqa #40204 displays a very lenient opinion on the matter:

Shaykh al-Islam Ibn Taymiyah said in Majmoo’ al-Fataawa (21/451):
Whoever becomes junub whether as the result of a wet dream or intercourse – permissible or forbidden – has to do ghusl and pray. If he is unable to do ghusl because there is no water or because he will be harmed by using it – such as if he is sick and using water will make his sickness worse, or there is a cold wind and he fears that if he does ghusl he will become sick with a headache or cold or bronchitis – then he should do tayammum and pray. This applies equally to men and women. He (or she) does not have the right to delay the prayer beyond its prescribed time.”

as it allows performing Tayyamum, for people having actual health condition that might get worse (for a while).

Further in the same fatwa it is made clear that after performing Tayyamum -instead of ghusl- no new ghusl nor making up for worships is required. As Tayyamum is a full replacement for the water of ghusl.

Shaykh Ibn Baaz was asked in Majmoo’ al-Fataawa (10/201):
Does tayammum mean that the junub person no longer has to do ghusl at all? How many prayers may he offer with tayammum?

He replied:
Tayammum takes the place of water, as Allaah has made the earth a place of worship and a means of purification for the Muslims. If no water is available or the person is unable to use it because of sickness, then tayammum takes its place and remains sufficient until he finds water. When he finds water he has to do ghusl to cleanse himself of the previous janaabah. Similarly if the sick person recovers and Allaah heals him, he has to do ghusl to cleanse himself from the previous janaabah from which he had purified himself by means of tayammum, because the Prophet (peace and blessings of Allaah be upon him) said: “Clean earth is the wudoo’ of the Muslim if he cannot find water for ten years.” Then he said: “When you find water, then make it touch your skin.” Narrated by al-Tirmidhi from the hadeeth of Abu Dharr (may Allaah be pleased with him); narrated by al-Bazzaar and classed as saheeh by Ibn al-Qattaan, from the hadeeth of Abu Hurayrah may Allaah be pleased with him.

If the junub person finds water then he should make it touch his skin, i.e. wash with it. With regard to his past prayers, they are valid by virtue of the tayammum he did when water was not available or he was unable to use it, because of sickness that prevented him from using it, until the sickness ends and he recovers and until he finds water, if none was available, even if that takes a long time.

The same fatwa site islamqa #179041 offers an equivalent fatwa as that of islmaweb in which they clearly state that Tayyamum only is only allowed if water would kill you -there the question is about an asthamitic person-! And quoting a statement of imam an-Nawawi from his al-Majmo' المجموع شرح المهذب in the chapter about Tayyamum in case of presence of water and fear for the health:

sup>Here and in the following I'm translating from Arabic language, as this translation is of my own take it with the necessary care!
إذَا كَانَتْ الْعِلَّةُ الْمُرَخِّصَةُ فِي التَّيَمُّمِ مَانِعَةً مِنْ اسْتِعْمَالِ الْمَاءِ فِي جَمِيعِ أَعْضَاءِ الطَّهَارَةِ تَيَمَّمَ عَنْ الْجَمِيعِ ، فَإِنْ مَنَعَتْ بَعْضًا دُونَ بَعْضٍ غَسَلَ الْمُمْكِنَ وَتَيَمَّمَ عَنْ الْبَاقِي
if the reason allowing Tayyamum is hindering from using water for all the body, then one has to perform Tayyamum on his whole body. But if it applied for partly (certain body parts only) then one must wash the possible to wash and perfrom Tayyamum for the rest.

More quotes about Tayyamum vs. use of water in case of illness or injury

In an earlier part of his commentary an an-Nawawi divided illnesses that may be regarded as special cases for ghusl into three categories, here some quotes and a short explanation -not a full translation- of the content:

أَحَدُهَا : مَرَضٌ يَسِيرٌ لَا يَخَافُ مِنْ اسْتِعْمَالِ الْمَاءِ مَعَهُ تَلَفًا وَلَا مَرَضًا مَخُوفًا وَلَا إبْطَاءَ بُرْءٍ وَلَا زِيَادَةَ أَلَمٍ وَلَا شَيْئًا فَاحِشًا ، وَذَلِكَ كَصُدَاعٍ وَوَجَعِ ضِرْسٍ وَحُمَّى وَشِبْهِهَا ، فَهَذَا لَا يَجُوزُ لَهُ التَّيَمُّمُ بِلَا خِلَافٍ عِنْدَنَا

The first category: Light illnesses that allow using water without the risk of harm, nor prolongation of the illness nor additional hurt etc. an example of this are headaches, tooth aches and fever etc. in such cases Tayyamum is not allowed without any opposition in our school of thought. This is also the majority view. Only a few scholars from the maliki school of fiqh and the dhahri school of fiqh oppose it and refer to the verse above as an evidence.

الضَّرْبُ الثَّانِي ) مَرَضٌ يُخَافُ مَعَهُ مِنْ اسْتِعْمَالِ الْمَاءِ تَلَفُ النَّفْسِ أَوْ عُضْوٍ أَوْ حُدُوثُ مَرَضٍ يُخَافُ مِنْهُ تَلَفُ النَّفْسِ أَوْ عُضْوٍ أَوْ فَوَاتُ مَنْفَعَةِ عُضْوٍ ، فَهَذَا يَجُوزُ لَهُ التَّيَمُّمُ مَعَ وُجُودِ الْمَاءِ

The second category: Illnesses with which using water may cause harm to body (death), or parts of the body (require an amputation) or a propagation of an illness etc. in this case Tayamum is allowed this was the view of the majority of the shafi'i scholars with one exception. The shafi'is nevertheless also quoted 'Ata'a and al-Hassan al-basri who considered the verse to apply for ill person that can't find water. Be aware that the first quote I've mentioned above from al-Majmo' is the summary of all

( الضَّرْبُ الثَّالِثُ ) : أَنْ يَخَافَ إبْطَاءَ الْبُرْءِ ، أَوْ زِيَادَةَ الْمَرَضِ وَهِيَ كَثْرَةُ الْأَلَمِ وَإِنْ لَمْ تَطُلْ مُدَّتُهُ أَوْ شِدَّةُ الضَّنَى

The third category: Illnesses that may grow or get worse or the pain getting harder due to the use of water. In this case performing tayyamum is allowed. And there's no need to make up prayers performed due to this case. This is the view of the majority of scholars like abu Hanifa, Malik, Ahmad, abu Dawod etc. however 'Ata', al-Hassan and Ahamd also prohibit tayyamum here.

Note that in all the above cases illness refers to injuries too!