The causes of itchy lower eyelids are as follows.
If the itchy lower eyelid is accompanied by significant redness and swelling, consider contact dermatitis, where the patient may have been exposed to poor quality cosmetics, allergy medications, irritating objects, etc. causing allergies.
If there is a tender lump on the lower eyelid to touch, it may be blepharitis caused by a bacterial infection. Early onset eyelid redness and swelling is not obvious, and some patients may present with itchy congested eyelids.