Praise be to Allah, and may Allah’s peace and blessings be upon the Messenger of Allah, his family and his companions.
As to what follows:
In response to your question, we say, and with Allah Almighty lies all success:
I do not recommend her to haste her menstruation, for if she does, the period may be longer. But if she is able to delay it, she may do so, on the condition that it does not harm her, and that it is by consultation of a doctor that specializes in this field. That is because some pills have side-effects on the woman, and also that some pills do not stop the period completely, meaning that the period may stop but some blood will continue to leak, thereby becoming an obstacle in her worship, and making her uncertain: “Am I in a state of purity or impurity? Am I menstruating or not?” So in this case, she must see a doctor in order to take the right amount that will not cause her harm.
Whereas if it causes harm to her or messes up her pattern of menstruation, then she should not take these pills. And if she had her period, then all praise is to Allah. As `A’ishah, the mother of believers, the wife of the Prophet (peace be upon him) went for Hajj and had her period at Sarf (a place between Makkah and Madinah), so she started crying. The Prophet (peace be upon him) came to her while she was crying, so he said, “What is the matter?” So she said, “I am having my period.” The Prophet (peace be upon him) said, “That is a matter ordained by Allah on the daughters of Adam.” Meaning: you are not the only one affected by this, and this consoles the one affected. So he said to her, “Do whatever the pilgrim does, but do not perform tawaf around the ka`bah.” So she is only prohibited from performing tawaf. As for everything else (required in Hajj), then she is allowed to do… from standing on `Arafah to sleeping at Muzdalifah, stoning and sleeping at Mina, and all other acts that must be performed. Except for tawaf, and sa`i, because it is a follow-up of tawaf. So she waits until she is pure, then she performs her tawaf after that.
Some women also assume that if they had their period, they cannot enter into the state of ihram at the Miqat. There is no problem with entering into ihram at the Miqat, as Asma’ bint `Umays (may Allah be pleased with her) – as reported by Jabir in Sahih Muslim – gave birth at the Miqat. So the Prophet (peace be upon him) ordered her to fasten a cloth around her private part and take a bath, and allowed her to continue with her Hajj.
This brings to point a question often brought up: Is it from the requirements of udhiyah (offering a sacrifice on the days of Hajj) that a woman avoid combing her hair? The answer is: no, it is not a requirement of udhiyah to avoid combing one’s hair. Some may say: my hair falls when I comb it. So we say: there is no prohibition in combing, go ahead and comb. You are only prohibited from removing hair voluntarily, which is by cutting, shaving, or plucking. As for what falls while setting the hair, then there is no source (from the Qur’an and Sunnah) that says, “If you intend to offer sacrifice, avoid combing your hair.” Rather the Prophet (peace be upon him) ordered `A’ishah (may Allah be pleased with her) to comb her hair while she was in the state of ihram, as mentioned in Bukhari and Muslim, in `A’ishah’s narration, the Prophet (peace be upon him) said, “Undo your hair and comb it, and delay your umrah.” Some hairs may falls out when combing them, so there is no prohibition in combing. Likewise, using a blow dryer and other styling equipments, there is no harm in that, nor does it affect the soundness of the udhiyah.
Some people avoid offering the sacrifice because of these concerns, to which I say: It is not except a matter of days that will pass by and be over, and it is upon us to feel the true meaning of worship in these days (the first ten days of Dhul-Hijjah) and look forward to a reward from Allah for things we are prevented from doing (due to udhiyah, such as cutting nails, hair, etc.), which in other days, we may go for weeks, and in the case of some people, months without thinking about cutting their hair or removing something from their skin (as in plucking, etc.). Yet when the prohibition comes for a limited number of days, the question arises: should I or should I not?
And Allah knows best.