Lena Dunham has developed rosacea.

The 31-year-old actress' has admitted her favourite feature was her ''good skin'' and has said she was often complimented on her complexion, but after taking a course of steroids to treat ''joint pain'', the star was distraught to find her face covered in the common skin condition which looks like ''tiny pimple-blisters''.

Writing in her most recent Lenny Letter, the 'Girls' creator said: ''A few weeks ago, a course of steroids to treat a massive flare of joint pain and instability led to rosacea's appearing overnight, making me look like a scary Victorian doll, two perfect pink circles painted on her porcelain face. 'It's actually pretty cute,' my mom said. 'Very '90s editorial fashion!'

''Then, after a long, sweaty night shoot in which I was covered in strange makeup, I washed my face to reveal that the rosacea had become hundreds of tiny pimple-blisters that covered me from forehead to neck. The sound that came from that hair and makeup trailer was similar to when the b***h in the 'Craft' starts losing her hair in the locker room. Terror, rage, and piteous sadness. My face burned, but not as badly as my pride.''

And Lena admits that she often used to be ''lazy'' about taking care of her complexion because it was always ''glowing'', and was ''hysterical'' when her rosacea appeared.

She continued: ''I got used to having good skin over the years. Showing up to photo shoots and being told, 'You barely need any makeup at all!' Having other women ask my secret (maybe she's born with it, maybe it's Terri Lawton.) Gradually I got lazy about my products, but my skin remained dreamy, even through hormone fluctuations, new medications, and daily, sweaty on-set makeup wear. Sometimes I forgot to wash my face, and I still glowed. It started to feel like a superpower.

''Until I found myself 31 and hysterical, in the dermatologist's chair as she extracted infected areas, applied an antibiotic cream, and explained that rosacea is another chronic condition: once the cat's out of the bag, there's no guarantee she's headed back in. The acne on my shoulders and back was also steroid induced, she explained.''

Lena is taking her skin condition in her stride though, as she wants to show young people suffering with acne that ''nobody is immune'' from these conditions.

She wrote: ''What scares me most is that female celebrities with access to skin witches are not the primary targets of this kind of relentless hatred. We've got the resources to deal in every possible way. But there are millions of teenagers applying the entirety of their time, resources, and wit to attacking classmates in painfully inventive ways. I'm starting to believe that speaking this pain aloud isn't just good for my own healing: it allows any young woman who might be watching to understand that nobody is immune from feeling bad about hateful attention.

''I love myself. I think I'm grand. I hear the voices of the Internet when I get dressed. I have a bunch of blister-pimples. All are true. All are fine. None are forever. I promise you.''