The High pin output will always be +5V. If you put a 50 Ohm resistor, it should have a current of 100mA.
But the UNO's digital pins support a maximum of 40 mA.
So if you try to drain more than 40 mA, you could damage the pin.
How are you measuring the current?
PS:
See this informative image about the current that the pins can supply.
