What causes black discoloration at the base of the big toe?

Nov 28, 2025 Source: Cainiu Health

Dr. Li Feng

Introduction

In general, black discoloration at the base of the big toe may be caused by dye from socks or shoes, external pressure, onychomycosis (fungal nail infection), paronychia (nail fold inflammation), or diabetic foot. If discomfort occurs, it is recommended to seek timely medical evaluation and treatment at a正规 hospital. In daily life, choose well-fitting, breathable footwear and socks; trim toenails properly, avoiding cutting them too short; and maintain clean, dry feet.

Generally, black discoloration at the base of the big toe may be caused by dye transfer from socks or shoes, external compression, onychomycosis (fungal nail infection), paronychia, or diabetic foot. If discomfort occurs, it is recommended to seek timely medical evaluation and treatment at a正规 hospital. Specific causes are analyzed as follows:

1. Dye Transfer from Socks or Shoes

Dark-colored socks or shoes are prone to fading. With prolonged use, dyes can adhere to the skin or nail surface of the toes, causing black discoloration at the base. Switch promptly to light-colored cotton socks and footwear. Soak feet in warm water and gently wipe the affected area. Avoid wearing low-quality socks or shoes that easily fade.

2. External Compression

Tight footwear or trauma during exercise can cause capillaries at the base of the toe to rupture and bleed, leading to blood accumulation and black discoloration. Wear loose, breathable shoes to reduce foot compression. Apply cold compresses during the acute phase to stop bleeding, and switch to warm compresses later to promote absorption of the hematoma.

3. Onychomycosis

Fungal infection of the nail plate and underlying tissue damages the nail structure, resulting in black discoloration, thickening, and brittleness. Follow medical advice to use terbinafine hydrochloride cream, itraconazole capsules, or fluconazole tablets. Keep feet dry and avoid sharing footwear or socks with others.

4. Paronychia

Bacterial infection due to overly short nail trimming or injury leads to inflammation of the nail fold, causing redness, swelling, and pus formation. In later stages, local tissue ischemia and necrosis may result in black discoloration. Under medical guidance, topical mupirocin ointment or oral cephalexin capsules and amoxicillin capsules may be used. Surgical incision and drainage are required if an abscess develops.

5. Diabetic Foot

Diabetes-induced peripheral vascular disease impairs blood circulation in the lower limbs, leading to ischemia and hypoxia in the toes, which manifests as blackened skin and numbness. Strictly control blood glucose levels. Use alprostadil injection, clopidogrel hydrogen sulfate tablets, or cilostazol tablets as prescribed. Severe cases may require lower limb bypass surgery. Avoid foot injuries in daily life.

In daily life, choose well-fitting, breathable footwear and socks; trim toenails properly without cutting too short; maintain clean and dry feet; keep blood sugar stable; and perform regular foot examinations to reduce the risk of abnormal black discoloration.

View All

What causes fluid to leak from under the big toe nail, and what should be done about it?

In general, fluid accumulation under the big toenail may be caused by trauma, moist irritation from non-breathable footwear or socks, paronychia, infected onychomycosis, or pyogenic granuloma. Depending on the specific situation, treatment options such as conservative management, medication, or surgical intervention can be considered to improve the condition. In daily life, it is important to wear breathable shoes and socks, keep the feet dry, avoid toe injuries, and avoid cutting toenails too short.

View Full Answer

Why is my big toenail becoming increasingly thick and bulging, and what should I do about it?

In general, increasing thickening and bulging of the big toenail may be caused by aging, prolonged pressure, onychomycosis (fungal nail infection), nail dystrophy, or nail psoriasis. Depending on the specific situation, patients can choose appropriate treatments such as conservative management, medication, or surgical intervention to improve the condition. In daily life, it is important to wear proper footwear and socks to protect the nails, avoid trauma and compression, and maintain a balanced diet to ensure adequate nutrition.

View Full Answer

What to do if a blister forms on the big toe due to friction

In general, blisters on the big toe may be caused by ill-fitting shoes, excessive physical activity, weakened skin barrier, bacterial infection, or early signs of diabetic foot. It is recommended to seek medical attention promptly, identify the underlying cause, and then improve the condition through general care, medication, or other treatments under a doctor's guidance. In daily life, keep the feet clean and dry, and avoid puncturing unbroken blisters yourself.