(female) I have been taking Hyzaar 50/12.5, a high blood pressure medication, for several years and I am experiencing balding in the top of my head and thinning around the edges; before taking this medication I had a full head of hair. Is there a high blood pressure medication that would possible not cause hair loss or thinning?
Hyzaar is known to cause hair loss in some people (“alopecia” is listed as a side effect). The pill is a combination of hydrochlorothiazide (HCTZ) and losartan, and I’ve written about HCTZ before. That being said, blood pressure medication is not generally the first thing doctors look for when evaluating hair loss in women. There are many other medical conditions that contribute to hair loss in women and these should be evaluated by your primary care physician. Some (but not all) of the causes can be anemia, thyroid conditions, menopause, genetic, lupus, etc. (see here).
Good question. Propecia (finasteride 1mg) blocks mainly DHT type II, and Avodart (dutasteride) blocks both DHT type I & II. You would think if you block ALL the DHT it would be better against androgenic alopecia. Dutasteride is three times more potent than finasteride inhibiting the type II enzyme and 100 times more potent than finasteride inhibiting the type I form of the DHT producing enzyme. There are clinical observations that suggest that dutasteride is better than finasteride, but it is not approved for hair loss by the FDA and the long term safety on human reproduction for dutasteride (reports of sterility is a complication) have been suggested in some rare patients. We have received many reports by varying doctors who switch people from finasteride to dutasteride and get a better response. The next logical question should be: If we increase the finasteride dose to 5 mg or so, will it be better to treat hair loss? I don’t know if anyone really knows that answer for sure. Some of the original studies on finasteride suggested that the 1mg dose is the most universal dose, but it may be that a high dose in those who are refractory to finasteride may help. Some doctors are using a higher dose of finasteride on long term users. It’s a prescription drug, so I’m not suggesting you should take a higher dosage. The problems for either finasteride and dutasteride is that side effects rise when increasing dosages.
Cellcept (mycophenolate mofetil) can cause hair loss as a side effect of the drug. This drug is used in organ transplantation to prevent rejection of organs like the liver, kidney, or heart. Hair loss is listed as a common side effect of Cellcept on pharmaceutical company 
Yes, Xolair (omalizumab) has been reported to produce hair loss in some patients. I don’t have anything else to add, as I don’t use nor do I prescribe this medication (I do not treat patients for asthma ailments). Sorry.