Can seborrheic dermatitis interfere with hair growth?

Not really... Seborrheic dermatitis is an inflammatory condition thought to be related to an over abundance of a bacteria called pityrosporun ovale. The immune system recognizes this bug and attacks it and in the process causes the skin to get inflamed red and itchy. This induces scratching which can then lead to hair breakage which gives one the impression that they are loosing hair but the root is not damaged.
Yes. If the scalp is inflamed from excess oil buidup, hair can fall out. See your pcp or better yet a dermatologist to treat your sebderm (shampoos, lotions) and explore the possibilities of other causes/contributors of hair loss. Good luck!