Abstract: Tension-type headache is treated by interacting with neuronal transmission in relation to pain in connection with headache in a way which prevents or decreases sensitization of second order nociceptive neurons. In particular, treatment is performed by administration of an effective amount of a substance which prevents or decreases central sensitization. Important examples of such substances are substances which interact with nitric oxide, such as nitric oxide synthase (NOS) inhibitors, such as L-NMMA or L-NAME or L-NIO or L-NNA. According to a broader aspect of the invention tension-type headache is treated by administration of substances which are effective in preventing or decreasing pain in connection with tension-type headache, such as the substances mentioned above.