Hi Dhanya,
We all happen to take extra care of our face but tend to overlook areas like neck, elbows and knees and we dont bother untill the problem gets aggravated...darkening of elbows is not a big deal....u dont need any costly medicine....just follow few tips and soon ur elbows would shine like ur face:
1.Use ur face scrub regularily on ur elbows so that the hardened skin gets sloughed off.....plz do it tenderily.u can safely do this every alternative day.In case u dont have face scrub, u can make one at home...u can mix sugar granules wid lemon juice and use it as a scrub.
2.Keep ur elbows moisturised. u can use a good moisturiser wid sunscreen or can also apply almond oil.
3. At nite before sleeping, apply a mixture of glycerine, rose water and lemon juice.This would help in getting rid of darkness and would also make the elbows soft.Doing this regularily would surely make difference.
Remember to give 10 mins everyday towards ur elbows and they would shine.
Hope this helps
Cheenu