This is a good effect from dutasteride 0.5mgs daily
Why did my hair fall out when I started finastride?
Some people taking finasteride may lose hair when starting the drug. That means that the drug is forcing some hairs to switch where they are in their hair cycle and the drug is working. Hairs that fall out, will then go into anagen, and commence a new hair cycle with DHT being mostly blocked.
https://ecerm.org/upload/pdf/cerm-2024-07675.pdf
Conclusion: Long-term use of dutasteride may lead to male infertility by persistently impairing semen volume and sperm motility.
If someone took finastride their whole life and stopped at 80 would they go right to where they would have been if they never were on fin at all?
This hypothetical question is not straight forward. First, assuming that this 80 year old man had unherited a Class 7 pattern of balding and that finasteride was 100% effective at stopping hair loss. With this assumption, I am sure that he would revert back to his inherited pattern within a few months.
These are two cases reversed using Tofacitinib along with other chemotherapy. The doctors reported that this often does not last and requires frequent re-treatments. See here for definition of the disease: https://en.wikipedia.org/wiki/Alopecia_totalis
Although blocking DHT almost completely, is, theouitically, able to prevent hair loss for a very long time, there is also a genetic component in which the number of hair cycles of hairs within the balding pattern distribution is also subject to limitations. For example, if a specific young man is genetically going to develop a Class 3 pattern of balding, then if it he gentically programmed for 7 hair cycles of three years each on the life of these hairs, and these hair then die at the end of the 7 hair cycles (all at the exact same time for the purpose of this model), dutasateride can only prolong the hair cycles, not the number of hair cycles. So a simple math formulae would predict 7 hair cycles of 3 years each developing a Class 3 pattern of balding would appear immediately at 21 years of age (3 times 7). IF the cycles were prolonged to 4 years because of the drug (theoritically you start dutasteride when you are born for this calculation to work), then 7 cycles multipled by 4 years each, get you to an age of 28 before you develop that Class 3 pattern, all at once for this model. One morning you wake up, and in the shower your hair falls out and you develop an instant Class 3 pattern because your vulnerable hairs are at their life. those hairs within the Class 3 pattern. Of course, the hair cycle length varies by age and sex thoughout the formative years and within the pattern of balding, the hairs vary with their life expectancy. So simple calculations like those above make no sense, but it does show the complexity of making sense out of predicing hair loss with drugs like finasteride and/or dutasteride.
I hope that you had fun reading this.