Blood blisters appeared on the hand.

Blood blisters on the hands may be caused by mosquito bites, folliculitis, urticaria, or other reasons, and treatment should be based on the specific condition. Details are as follows:

1. Mosquito bites

After a mosquito bites the skin, its secretions can irritate the underlying tissue, causing local capillary dilation and resulting in bumps, pain, and other symptoms. Treatment may include topical application of erythromycin ointment or oral administration of levocetirizine hydrochloride capsules under medical guidance.

2. Folliculitis

This is usually caused by friction from external substances or bacterial or fungal infections damaging hair follicles. Inflammatory stimulation may lead to swelling, redness, and other symptoms. Treatment may involve using mupirocin ointment topically or taking cefuroxime axetil tablets orally as directed by a physician.

3. Urticaria

This typically refers to a condition caused by temporary dilation of small blood vessels in the skin and mucous membranes, manifesting as sudden appearance of red bumps over the body, sometimes accompanied by itching. Medications such as urticaria pills or ebastine tablets may be used under medical supervision.

In addition to the above causes, similar symptoms may also result from eczema, dyshidrotic eczema, or hand fungus. It is important to maintain proper hand care and avoid using alkaline substances.