Having blue or pink nails can be concerning, but is often harmless. There are a few potential causes for this discoloration that are important to understand.
Quick Overview
The most common reasons nails may turn blue or pink include:
- Bruising under the nail from injury
- Fungal infections
- Bacterial infections
- Nail polish or other pigments
- Poor circulation or oxygenation
- Medications
- Autoimmune conditions
While some of these causes are harmless, others may require medical treatment. Checking with your doctor is recommended, especially if the discoloration is severe, spread to multiple nails, or accompanies other symptoms.
Underlying Causes
Bruising Under the Nail
One of the most common reasons for blue, black, or brown discoloration of nails is bruising or bleeding under the nail plate. This can occur from trauma such as jamming the finger in a door, dropping something on the nail, or other injury. The discolored area may start small and spread outward over several weeks as the bruise progresses. Often the bruising eventually grows out with the nail over time.
Fungal Infections
Fungal infections are a very common cause of nail discoloration, especially yellow, white, or brown nails. The medical term for this is onychomycosis. It occurs when fungi such as dermatophytes or Candida infect the nail bed and plate. In mild cases, it shows up as white spots or streaks on the nails. As it worsens, the nail can become thickened, distorted, crumbly, and very discolored.
Fungal infections often start at the tip or sides of the nail and then spread toward the cuticle. They can affect toenails, fingernails, or both. Having this condition on one nail puts other nails at increased risk. Warm, moist environments encourage fungal growth, making swimming pools and showers prime locations for transmission.
Bacterial Infections
While less common than fungal infections, bacterial infections can also invade the nails and cause discoloration. The medical name for this is paronychia. It often starts with redness, swelling, and pain around the nail or cuticle. Pus may be present. As the infection worsens, nails may turn yellow, green, black, or brown.
Cuts in the skin around the nail, chronic nail biting, finger sucking, aggressive manicures, or other trauma increase the risk of these bacterial infections. They require antibiotics to treat properly.
Nail Polish, Dyes, or Pigments
Using certain nail polish colors, especially dark reds and blues, can stain the nails even after removing the polish. The pigments soak into the nail plate and can leave a residual tint. This is common with cheaper polish or nail art with several colors layered on.
Other topical products like hair dye, ink, silver nitrate, or chemicals may also discolor the nails if they come into contact. Generally these pigments fade over time as the stained part of the nail grows out.
Poor Circulation
Proper blood flow and oxygenation are essential for normal nail color and growth. Some conditions can decrease circulation to the extremities. These include peripheral artery disease, Raynaud’s syndrome, hypothermia, and some cardiovascular conditions.
With poor circulation, nails may turn purple, blue, grey, white, or black. The skin may also appear pale or dusky. The nails alone can discolor, or it may accompany blue lips or feet. Treatment depends on the underlying cause.
Medications
Some medications are known to cause nail discoloration, including:
- Antimalarials like hydroxychloroquine can cause green-blue nails
- Cyclophosphamide and other chemotherapies can make nails dark
- Antibiotics like metronidazole may cause dark nails
- Gold therapy for arthritis can result in gray-brown nails
- Psoralen UV light therapy can induce brown-black color
When medication is the likely culprit, the discoloration often appears in horizontal stripes reflecting nail growth at the time the drug was taken. Discuss any new nail changes with your doctor.
Autoimmune Conditions
Some autoimmune diseases are associated with nail discoloration and other nail abnormalities like pitting, ridges, fragility and thickening. Examples include:
- Alopecia areata – Can cause white spots or patches on nails
- Psoriasis – Commonly causes pitting, yellow-red discoloration and separation of nail plate
- Lichen planus – May result in blue, dark red, or black nails with surface ridges
- Scleroderma – Leads to intense blue nail bed color in fingers
The nail changes correlate with disease activity, so they act as a helpful gauge for doctors to monitor progression.
When to See a Doctor
Consult your physician if your nails become profoundly discolored or the changes do not resolve on their own within several months. Seek prompt medical care for:
- Pain, swelling, redness, discharge or other signs of infection
- Nail separation from the nail bed
- Total discoloration of all nails
- Discoloration accompanying other concerning symptoms
- Changes that impair daily living
Diagnostic tests may be recommended to pinpoint the exact cause. For fungal and bacterial nail infections, laboratory analysis of nail clippings can help guide treatment. Underlying conditions leading to poor circulation or autoimmune symptoms will also need to be addressed.
Treatment Options
Treatment depends on the underlying reason for the nail discoloration:
- Bruising – Usually heals on its own over several months as the nail grows out
- Fungal infections – Topical or oral anti-fungal medication, with possible nail removal for severe cases
- Bacterial infections – Antibiotic therapy, possible surgery if severe
- Nail polish or dyes – Gently scrub nails to remove residue, discoloration fades over time
- Poor circulation – Treat underlying cardiovascular condition, keep nails short and dry
- Medications – May resolve after stopping medication, discuss options with prescribing doctor
- Autoimmune conditions – Treat the underlying disease, keep nails trimmed
Home care tips can also help prevent fungal and bacterial infections from starting or worsening:
- Keep nails trimmed short and filed smooth
- Thoroughly dry hands and feet after washing
- Don’t share nail care tools with others
- Wear shower shoes in public areas
- Treat chronic conditions like diabetes that increase infection risk
- Avoid nail damage from biting, picking or aggressive manicures
Outlook
Blue, black, or pink nails often simply reflect bruising or staining and are nothing to worry about. However, profoundly dark, abnormal, or painful nails could signal an underlying health condition needing treatment. Fungal infections also require proper antifungal therapy.
With time and appropriate care based on the cause, discolored nails commonly return to their normal hue. Some staining may remain internally even after the nail looks normal on the outside. But this is just a cosmetic issue. Focus on getting any infections under control, and the appearance should improve.
Conclusion
Nail discoloration is common and usually harmless, but can sometimes indicate an underlying problem. Blue, black, or purple nails may result from bruising, fungal infections, bacteria, medication side effects, illnesses, or circulation issues. Most causes are treatable, especially if caught early. See a doctor if the discoloration is severe, persistent, or spreads to rule out infections or other medical conditions needing care. Addressing both the appearance and root cause can help get nails back to their healthy color.
