The phrase "to increase the dose" means to take more of a medicine or substance than before in order to make it stronger or more effective. Full definition
Their analysis showed that the risk of stomach cancer increased with increasing doses of radiation to the stomach. (sciencedaily.com)
Gradually increase the dose until you go once or twice a day. (mindbodygreen.com)
Very few side effects were reported at the average level, and none of the symptoms appeared to increase in frequency with increasing dose. (additudemag.com)