I have a condition called POTS (postural orthostatic tachycardia syndrome) which causes me to have poor circulation and to get super tired. I had heard on the radio of how B-12 supplements can help POTS patients with their tiredness and circulation. So, I decided to give Spring Valley Sublingual B-12 2500 mcg supplement a try. I took one pill a day and hated the taste. You are suppose to leave the tablet under your tongue for 30 seconds to get it to dissolve before swallowing. I had to take a drink of water as soon as the 30 seconds were up, to get the bad after taste the B-12 supplement left in my mouth. I ended up taking the supplement for 2 months and I honestly didn't feel any difference. The Spring Valley B-12 supplement was suppose to help boost my metabolism, but it still left me feeling tired. I didn't feel any boost of energy. My condition causes me to get light headed and dizzy from having such poor circulation. But, the supplement didn't really help with my poor circulation symptoms. If the Spring Valley B-12 supplement did work with my circulation problem, then it was just too small to notice any major difference. I was a little disappointed that the Spring valley B-12 2500 mcg supplement didn't help me with my circulation and tiredness problem. Even though it didn't work for me doesn't mean it wouldn't work for you.