Yes Rogaine works. Generic Minoxidil also works. How well it works depends on how long hair has been gone from those sparse or bare areas. If those areas are completely void of hair and have been that way for a long time (five years or longer), nothing is going to work to grow hair there. If it has been less than five years, you might be able to grow some of it back. You won't know untill you try.
Here is what I suggest. If you are in the U.S., go to WalMart or whatever store you prefer and pick up one bottle of Rogaine foam and Nizoral A-D shampoo. Use the foam once per day about two hours before bedtime. Use Nizoral A-D shampoo once per week in place of your regular shampoo.
One bottle of Rogaine foam should last 30 days but since you will only be using it once per day you will have only used half of it in 30 days. There are two reasons I am suggesting you start out this way. First to find out if you can use Rogaine. Most people can but some people can't. So you only want to buy one bottle just in case you are one of the few people who can't use the medicine. The other reason is so you have time to learn how to dose yourself properly. It takes some practice. You will understand what I mean once you start.
After 30 days if all is well, go back to the store and get a 3-month supply of Rogaine foam and a 3-month supply of generic liquid 5% Minoxidil. Use the foam for your morning dose and the generic liquid Minoxidil for your evening dose. There are two reasons why I suggest you do this. First it is because it takes four to six months before you will know if Rogaine or generic Minoxidil is going to help you. This way you will already have a six month supply. The second reason is to help you save some money. Rogaine foam is more expensive, but it is very stealthy. Generic liquid Minoxidil is inexpensive but it is not stealthy at all.
Rogaine currently has a rebate promotion going on. Once you buy the 3-month supply of Rogaine foam, take advantage of the rebate promotion. Here is a link to the form and Rogaine's website.
Continue to use Nizoral A-D shampoo once per week in place of your regular shampoo as part of your regimen.
Take good quality photos before your start your regimen. After six months take a second set of good quality photos. You want to keep your before and after photos as similar as possible to help you make the best evaluation and comparison you possibly can to help you determine if the medicine is working for you.
Remember, it takes four to six months to determine if Minoxidil will help you. It takes longer before you will know how well it can help you. If between four and six months you start seeing peach fuzz, the medicine is working for you. You will not know how well it is going to work for you until you have been using the medicine for 12 to 18 months.
If after six months it is obvious that the medicine is not going to help you, go off of it gradually. Stop using it twice per day and use it only once per day for a few weeks. Then only once per day every other day until you run out of the medicine. This is to help you avoid the shed that sometimes happens when people go off Minoxidil.
My best to you,