Yes it can, and if you look closely it might be ridged too. I have this on my fingernails more promenently which is a known side effect. Nails can also become brittle. These side effects are usually dose dependent too. They are supposedly harmless but alittle disfiguring!

While on hydrea, I had issues with hair, skin, and nails. My fingernails darkened to a deep purple color. I've been off HU for three years, and my nails are back to normal as is my hair. My skin is still problematic, but at least no new skin cancers.

Yes it does, Nails and toenails, and sometimes skin. It comes and goes, depending on the dosage.

Dark lives on toe or fingernails often signal current or possible melanoma, etc.

Please see a Dermatologist, and other Specialist.

Thanks for the info.