Praise be to Allah.
Can Muslim women adorn themselves?
Allah has permitted women to adorn themselves for their husbands, and He has permitted them to adorn themselves in front of other women and mahrams , but this adornment is not permissible if it involves anything that goes against shari’ah.
So it is not permissible to apply cosmetics that will cause her physical harm, and it is not permissible for this adornment to involve changing the creation of Allah. Kohl, henna and the like do not involve changing the creation of Allah, unlike filing the teeth, plucking the eyebrows and tattoos -- these things do involve changing the creation of Allah with regard to shape and colour, hence these actions are haram and are major sins.
‘Abd-Allah ibn Mas’ud (may Allah be pleased with him) said: May Allah curse the one who does tattoos and the one who has a tattoo done, the one who plucks eyebrows and the one who has her eyebrows plucked, and those who file teeth for the purpose of beautification, changing the creation of Allah. (Narrated by al-Bukhari (5931) and Muslim (2125)
Are lip fillers haram?
One of the things that is similar to these haram actions is that which is mentioned in the question of putting creams to make the lips swell . This is unlike putting colour that is permissible and is not harmful to the lips, because that does not fix a colour permanently like tattooing ; rather it is temporary and is no different from the ruling on henna and kohl for the eyes.
Hence it seems to us that making the lips larger with these cosmetics is not permissible, because it is changing the creation of Allah. Even worse than that and more haram is having surgery to make the lips bigger.
Such things are unknown except in the case of weakness and defeatism and blind following of the kafir west. These women are not content with the way Allah has created them; rather they have started to tamper with their bodies, making things larger or smaller and seeking beauty in something other than that which Allah has created.
Some of them have become a laughing stock among people when they made their lips so big that they looked like the lips of a camel! This is how people who saw them commented on them.
Feel proud of your Religion
So the Muslim woman should feel proud of her Religion and morals and the rulings of Allah's laws, and she should keep away from imitating kafir and immoral women. Allah has permitted her to use many things as adornment and He has not forbidden her anything except that which is harmful to her body, attitude and religious commitment.
In our answer to question number 1006 we have mentioned various kinds of cosmetic surgery and we have stated that among the kinds of such surgery that are haram is surgery to enlarge or reduce the breasts. This is like the ruling on enlarging the lips, so please refer to this question.
This ruling applies if the swelling of the lips is permanent, however, if it is as mentioned in the question, that the effect is temporary and the lips return to their normal state, then there seems to be no objection as long as the means used is not harmful. In this case, enlarging the lips can be compared to cosmetics that give colour to the skin temporarily, then fade away.
Please see also the answer to question number 47694 .
And Allah knows best.