def hashtag(text):
    res = re.findall('#.+', text)
    return res

In [51]: s = "blah-blah, #tag1 blah-blah, #tag2, blah-blah"

In [52]: tags = re.findall(r'(#w+)', s)

In [53]: tags
Out[53]: ['#tag1', '#tag2']