A red, blotchy line on the skin can be worrying, especially if you’re living with hidradenitis suppurativa (HS). People with HS often watch their skin closely for changes, so noticing a new mark can raise questions. While some marks may be related to HS, others may have different causes.

Understanding what HS usually looks like and when to seek medical care can help you feel more confident in your skin and improve your quality of life.

What Does HS Skin Typically Look Like?

HS is a long-term skin condition that causes small, painful lumps to form, particularly in areas where skin rubs together, like the armpits, groin, and under the breasts. HS can also lead to abscesses (inflamed pocket of pus) and eventually scarring.

HS lumps usually appear round, oval-like, or stretched out in shape. These lesions may appear red or pink in color on lighter skin tones and purple, brown, or gray on darker skin tones. They can also break open to drain fluid and cause thick or ropelike scars to form due to repeated HS flares.

While HS can cause many different skin changes, a simple red line usually isn’t one of the typical symptoms.

Can HS Cause a Red, Linear, or Blotchy Mark?

Even though HS doesn’t typically cause straight lines, there are a few situations where marks may appear somewhat linear, blotchy, or streak-like, including:

1. Inflamed Sinus Tracts

Sinus tracts are channels or tunnels that develop under the skin and often form between HS cysts. These sinus tracts may make it easier for certain types of infections or inflammation to travel between cysts, which may cause red, line-like appearances.

2. Scarring From Repeated Flares

Long-term HS can lead to ropelike scars from constant healing and reopening. These scars may even look like lines, especially in areas with sinus tracts.

3. Friction-Related Irritation

Some people with HS notice more irritation in areas with a lot of friction, such as areas where the skin rubs together or folds. This may cause streaky or blotchy redness that could look like red lines. Sometimes wearing tight-fitting clothing can also worsen this irritation.

What Else Could Cause a Red Linear Line on the Skin?

There’s limited evidence on whether or not red, blotchy linear lines are a symptom of HS. Oftentimes, a red, straight, or streaky line is due to conditions other than HS. Some common possibilities include:

• Scratches or minor skin injuries — Even small scratches from nails or clothing can show up as red lines on the skin.
• Stretch marks (striae) — Stretch marks can cause scar-like lines in the skin that can look pink, red, purple, brown, or black. Sometimes these stretch marks can be irritating or itchy.
• Contact dermatitis — This is irritation from something touching your skin, such as soaps, detergent, shaving products, or certain fabric. It can cause red or itchy streaks.
• Fungal infections in skin folds — Natural yeast on the skin can sometimes overgrow and cause an infection, commonly in areas with skin folds. This overgrowth can cause moist, red patches on the skin that can be itchy.
• Cellulitis — A warm, painful, spreading red or discolored area may be a symptom of cellulitis, a bacterial infection that needs medical care. Talk to your doctor if you also notice increased swelling or if symptoms spread to other areas of the body.
• Lymphangitis — This is a red streak that spreads upward from an infection site and is often accompanied by fever, fatigue, and chills. This condition needs urgent medical attention.
• Hives — Raised, linear, itchy hives are sometimes the result of scratching or pressure on the skin in a condition called dermatographism.

If you notice red marks or lines on your skin alongside flu-like symptoms such as headache, fever, and chills, seek medical care right away, as these can be signs of an infection.

How Can You Track Skin Changes With HS?

Keeping track of new marks on your skin can help you and your healthcare team understand what’s happening. If you notice changes on your skin that may be related to your HS, try to note the location and pain level. If it’s warm or swollen, it may be a sign of an infection rather than HS. Check for any symptoms of HS, like drainage, to see if it’s similar to any of your past HS flares.

Be sure to pay attention to how long these skin changes last. A scratch usually fades quickly, but infections or other skin changes may take longer or even worsen over time.

It may be helpful to take photos of affected areas To Track any changes and share them with your dermatologist.

When Should You See a Doctor?

It’s a good idea to reach out to a dermatologist or primary care provider if:

• This is the first time you’ve noticed a mark like this.
• The area is painful, warm, or getting bigger.
• You have flu-like symptoms such as fever or chills.
• You notice changes in your HS patterns or severity.
• Your skin isn’t improving with your normal HS treatment options.

Even if you’re unsure, asking your healthcare provider for guidance can help prevent complications.

Drawing the Line on What’s Normal With HS

Red, blotchy, linear lines aren’t usually a common HS symptom, but similar line-like marks may be caused by HS-related sinus tracts, scarring, or friction irritation. Because many other conditions, like scratches or infections, can look similar, it’s important to watch for warning signs and seek medical advice when needed.

Join the Conversation

On myHSteam, people share their experiences with hidradenitis suppurativa, get advice, and find support from others who understand.

If you’ve noticed red blotchy linear lines on your skin, what turned out to be the cause? Let others know in the comments below.