I designed a PCB a while ago with an MCP23008 to drive some leds on a front panel. Now the frontpanel has been designed by someone else and they added red/blue leds (these ones: https://www.mouser.be/datasheet/2/678/HSMF_C146_DS103-1828432.pdf )

According the to datasheet the forward current for blue is 20mA while the forward current for red is 30mA.
The problem I see now is that the MCP23008 can only drive 25mA per pin.

So, driving the blue led shouldn't be a problem but red will actually need a transistor, right?
But there is no need for the led to have full brightness. Won't it work (with the correct resistor) without needing to redo the pcb for adding a transistor?

 

Hmm.. wait. I was looking at the absolute maximum ratings. I need some sleep I guess
The leds should be fine with 20ma I think.

 

The leds should be fine with 20ma I think.

Possibly less as even 20mA may be pretty bright.
Can you test them to see what current is actually needed for the desired brightness?

 

Modern LEDs are blindingly bright at 20mA. I usually use more like 5.

 

When the maximum allowed current is used for an LED then it gets extremely hot if it is in an air conditioned room.
With an ambient above 25 degrees C then at its max current it will melt and fail.