I would not typically expect any shock loss in the situation you describeTypically miniturized hair associated with hair loss is more vulnerable to shock loss. Rogaine however would be helpful to hedge your bet and can cause no harm. The foam works well. Start a few weeks prior to the HT and use it for the next 3 months.
An alternative to HT is a formal forehead reduction.
Hairline lowering with scalp advancement vs transplants.
There should be no shock from either procedure. Transplants will cost more and take multiple procedures and not look as natural as Irregular Trichophytjc Hairline advancement. Transplants give a texture change whereas advancement does not --ask your hair dresser. Make sure you go to a very experienced surgeon with this technique and look at his after results and you should NOT see a noticeable scar.
Shock loss can occur with any surgery or injury to the scalp. It is more likely to occur in those cases where hair was actively thinning such as pattern baldness of any type, traction hair loss, prior scalp surgery, scalp injuries or excessively dense packing of grafts. Shock loss is temporary, rarely severe, and the non balding hair follicles should start to regrow in 3 months similar to transplanted hair follicles. Minoxidil use before land after surgery may be helpful and unlikely to be harmful.
Female hairline lowering procedure
Shock loss in women with normal hair and a hairline lowering hair transplant procedure would be highly unusual
Shock loss is always a risk for any hair line surgery. It can start in the first weeks after surgery. Rogaine does NOT prevent
Shock loss is always a risk for any hair line surgery. It can start in the first weeks after surgery. Rogaine does NOT prevent shock hair loss.
Shock Secondary to Tansplants for Hairline lowering
It is normal to have temporary hair loss within the transplanted hair. However, shock withing the surrounding hair is very rare. You should also consider hairline lowering using the Irregular Trichophytic Hairline Incision so forehead reduction can be done in a single procedure with normal uniform density hair. The incision is hidden with hair growing through the new hairline.
Hair Line Lowering and Shock Loss
Shock loss after hair transplant to lower hair line with no hair loss is not really a worry if done properly. Make sure you see a well qualified doctor to assess you and plan an artistically beautiful hair line.