This rash has appeared on my thigh several days ago. It is very itchy and scaly. I have no idea what it is.
Your symptoms are suggestive of contact dermatitis.
Causes of Thigh Contact Dermatitis
Substances that can cause thigh contact dermatitis include:
1. Nickel from items of clothing like decorative studs that come in contact with the thigh.
2. Cosmetics and skin care products.
3. Fragrances from perfumes, soaps and lotions.
4. Medications applied on the skin
5. Plants like ranunculus, anemone, clematis, hellebore and mustards coming in contact with the skin for example during camping can cause irritant contact dermatitis. Chrysanthemums, sunflowers, daffodils, tulips and primula can cause allergic contact dermatitis.
Thigh Contact Dermatitis Treatment
The treatment of contact dermatitis involves:
Identify the causative substance and avoid it
Use mild cleansers
Use moisturizers liberally
Bland barrier creams with dimethicone like Cetaphil or those which contain ceramide like Cerave can be used to restore the epidermal barrier. Vaseline petroleum jelly can also be used. For maximum effect, moisturizers should be applied within 3 minutes of stepping out of the bath or shower, after the skin has been patted dry but while it is still moist in order to lock in as much moisture as possible. They may also need to be applied frequently during the day to keep the affected areas well moisturized.
Apply topical corticosteroids
Corticosteroid creams like amcinonide and fluocinolone can be are applied on the skin for around 1-2 weeks to treat contact dermatitis since they have anti-inflammatory properties. Corticosteroids are best applied 30 minutes after the moisturizer.
Take systemic antihistamines
Anthistamines that are taken by mouth can also be used to reduce the itch. Examples include the non-sedating fexofenadine (Allegra) and loratadine (Claritin) as well as the less sedating cetirizine (Zyrtec). The sedating diphenhydramine (Benadryl) and hydroxyzine (Atarax, Vistaril) are also used to reduce the itch especially if it disturbs sleep.