I only got a headache the first couple of times I took it. I have discs pressing on nerves in my lower back, bad enough that I can't function. Ultracet has given me pain free days. I've just had surgery on my elbow, and Ultracet has taken care of the pain. This is the FIRST pain med that hasn't made me sick to my stomach, and I've tried lots! The 'five days' max to take them worries me, but I can't be without the ultracet. This is great stuff!