Dry Skin (Xerosis): This is a common condition that can cause itchiness without any visible rash or skin irritation, especially in dry environments or during winter months. Itchiness is often worse in the evenings.

Eczema (Atopic Dermatitis): Although eczema typically presents with a rash, in some cases, the skin may appear normal between flare-ups, and the patient may still experience itchiness.
Keratosis Pilaris: A condition characterized by rough, dry skin that can feel itchy, often on the legs, but without a significant rash.
Contact Dermatitis: Allergic or irritant reactions can sometimes cause itchiness without a visible rash, especially if the offending agent has been removed.
Folliculitis: An inflammation of the hair follicles, which can cause itchiness, but the rash may be very subtle or only visible with close inspection.

Diabetes Mellitus: Itchiness can be an early symptom of diabetes due to high blood sugar levels affecting nerve endings and causing neuropathy.
Hepatic or Renal Disease: Certain liver or kidney diseases can cause itchiness (pruritus) without a rash, due to the buildup of toxins in the blood.
Hematologic Malignancies: Some blood cancers, like lymphoma or leukemia, can cause itchiness as an early symptom, often without any other visible signs.
Thyroid Disorders: Both hyperthyroidism and hypothyroidism can cause skin symptoms, including itchiness, sometimes without a rash.

Neurological Disorders: Conditions like multiple sclerosis, peripheral neuropathy, or neuromas can cause itchiness due to nerve damage or dysfunction.
Parasitic Infestations: Rarely, parasitic infections like scabies or hookworm can cause itchiness, especially at night, and may not always present with a visible rash.
Psychogenic Itch: A condition where itchiness is caused or exacerbated by psychological factors, without any underlying dermatological condition.