Hands with Red Spots

The red blotches on the hand are likely caused by contact dermatitis, a form of skin inflammation resulting from direct contact with irritants or allergens. Your skin can begin to recognize certain substances as either an irritant or an allergen. Any exposure to this particular material elicits an adverse response in the body, causing a rash to form on the surface of the skin. To ensure you're actually dealing with this skin condition, it's best to consult with a doctor.

Development

According to the Cleveland Clinic's website, contact dermatitis typically falls within one of two categories. The first and most common is irritant contact dermatitis, or ICD. This type of dermatitis develops when the skin comes into contact with acids, solvents, soaps or other chemicals. For some people, repeatedly immersing the hands in any one of these substances can eventually irritate the skin to a point where red blotches develop. You can read more about contact dermatitis.

The second type is allergic contact dermatitis, or ACD. With this type of dermatitis, your skin has an almost hypersensitivity to certain substances, like plants, metals, medications or other materials. Grabbing, touching or exposing the hands to something your skin recognizes as an allergen elicits an immune response from the body, causing antibodies to release chemicals that damage epidermal cells and leads to red blotches on the skin. 

Though not as common, MedlinePlus also lists "overtreatment" dermatitis as a form of contact dermatitis. This skin condition is usually the result of treatment for another skin disorder, which leads to skin irritation and subsequent symptoms associated with contact dermatitis. Since the skin is being irritated, this condition could fall within irritant contact dermatitis.