Is it permissible to get hair extensions?
Artificial hair (hair extensions) made from human hair or pig hair are unlawful (haram) according to explicit Prophetic narrations, and wearing them is absolutely impermissible. Nowadays, most hair extensions available in the market are made from human hair, therefore their use is not permissible.
However, if the extensions are made from materials other than human or pig hair (such as synthetic fibers or metals), and the purpose is not deception, not mere beautification, and not altering one’s natural appearance for adornment, but rather for medical treatment or concealing a genuine defect (for example, hair loss due to illness), then some scholars have mentioned conditional permissibility.
Nevertheless, after applying hair extensions, issues related to purity (taharah) in wudu and ghusl also arise. Moreover, various methods of extensions are prevalent in the market (such as clip-in, tape-in, micro-links, fusion, weave, etc.). Therefore, whichever method is adopted, it is necessary and obligatory to first ascertain the Shariʿah ruling regarding the validity of purification, and then act strictly in accordance with that ruling.
كما فی تكملة فتح الملهم: وقد اختلف العلماء فی التفصیل هذا الحكم علی اقوال الثانی الوصل بشعر الادمی حرام كذالك شعر نجس من غیر الادمی وأما الشعر الطاہر من غیر الأدمی فیجوز الوصل (إلی قوله) والذی یظهر من كتب الحنفیة أن الراجح عندهم القول الثانی. اهـ (ج۴، ص۱۹۱)-