All healthy people aged 18 and over can donate blood. In a preliminary examination, a doctor will check your suitability to donate blood. According to the DRK, men may donate up to six times within a year, women up to four times. There must be at least eight weeks between two donations. As long as donors drink enough water, avoid prolonged exposure and physical exertion in direct sunlight and observe the rest period of at least 10 to 15 minutes after donating blood, then nothing stands in the way of donating blood even in the heat, according to the DRK.