Jessica Simpson has opened up about her battle with eczema.

The 40-year-old revealed that she has suffered with the condition - which causes areas of skin to become itchy, dry, cracked, sore and red - since she was young but she credits EUCRISA with helping her it.

She wrote on Instagram: ''Y'all know I love connecting with you about life experiences. For the first time, I'm sharing that I've had eczema since I was a kid. After a recent eczema flare, I decided to talk to my doctor and was prescribed EUCRISA. While your experience may be different, EUCRISA really works for me. That's why I'm excited to partner with Pfizer, the makers of EUCRISA for mild-to-moderate eczema - to help inspire others with eczema to have the #EczemaConversation with their doctors like I did. You can get involved by sharing #EczemaConversation in your own way on your social media. If you or your little one have eczema, ask your doctor if EUCRISA could be right for you. #PfizerAd (sic).''

Jessica also shared safety information on the drug, including side effects, in her post.

Meanwhile, Jessica lost 100lbs last year by changing her diet.

The star ballooned to 240lbs when she was pregnant with her now- 17-month-old daughter Birdie but managed to get back to her pre-baby weight in six months thanks to some help from her trainer Harley Pasternak.

He told Us Weekly: ''It's not about the workouts. You don't lose weight doing biceps curls and lunges. You lose weight by changing your diet, hitting your step goal, working on your sleep ... those were the things she did so well.''

He also revealed that Jessica followed the principles of his 2013 book, 'The Body Reset Diet' and had three meals and two snacks a day with protein, fiber and healthy fat.