I guess you want to take nolvadex in order to prevent finasteride/dutasteride's estrogenic side effects, such as gynecomastia.
Tamoxifen (nolvadex) is a SERM (Selective Estrogen Receptor Modulator), which means that, depending on the tissue, it'll agonize or antagonize the ER. I suppose what worries you most is that it has an antagonistic effect in the scalp and thus promotes hairloss. Searching through some studies (1)(2) one can easily begin to gather some evidence which seems to lead to the conclusion that, as far as estrogen is concerned, its effect in the scalp is antagonistic.
It's also worth quoting some interesting statements from one of the studies, which seem to make clear that estrogen and alopecia tend to inversely relate each other:
"In areas of male pattern baldness oestrogens initiate hair growth and androgens cause the transformation of terminal to vellus hairs. Withdrawal of oestrogenic stimuli causes the hair follicle to shift into a resting phase. Tamoxifen and goserelin produce an environment of hypo-oestrogenism with relative hyperandrogenism, which leads to hair loss in susceptible women. In older women the follicle may not recover."
I personally think that Nolvadex is a very good SHORT term solution; i.e.: if gynecomastia begins to grow nothing will be as effective as stopping/reverting its growth as tamoxifen is. The problem is that, if you want to use it long-term, you might experience certain ocular toxicity problems which have been reported in several studies. So I wouldn't recommend it for long term use. You might use phytoestrogens, which don't seem to relate to ocular toxicity issues, instead of SERMS; however, the problem with the former is that you can never tell for sure whether its net effect is being agonistic or antagonistic, for that would strongly depend on your levels of estrogen.
What I generally recommend as the best choice is that of an aromatase blocker, such as anastrozole or letrozole. These differ from SERMs in that they don't interact with the ER; what they do is blocking aromatase enzyme, thus preventing the conversion of T to E; so this results in an antagonistic effect in all the tissues. However, these are expensive, so you might want to use an alternative such as red wine or red grapeseed juice, which might (more research is needed) be quite good in order to lower estrogen levels.
From my viewpoint, the main problem one faces when using an antiestrogen along with a 5AR blocker is that we cannot tell for sure how much of dutasteride's positive effects on scalp hair are a result of increased estrogenic activity. I mean, it might be possible that those positive results are not only produced directly by the blocking on DHT production and the subsequent AR binding, but also by the increased estrogenic activity which stems from that... that's something which would make sense taking into account the data provided by the studied I quoted.
1: BMJ. 1997 Feb 15;314(7079):481.
Alopecia and breast disease.
2: Ayoub JP, Valero V, Hortobagyi GN.
Tamoxifen-induced female androgenetic alopecia in a patient with breast cancer [Letter]. Ann Intern Med. 1997;126:745-6.
[PMID: 0009139575]
