The word “comorbidity” means having two or more health conditions at the same time. Research shows that people with seborrheic dermatitis often have other medical conditions. Examples include metabolic disease, bone and joint problems, and certain neurological (brain and nerve) disorders.

Scientists don’t yet know exactly what causes seborrheic dermatitis. They believe it’s probably a combination of factors, including lifestyle habits, environment, and genetics. Some of these same risk factors may also play a role in other health conditions. If you’re living with seborrheic dermatitis, learning about associated conditions can help you understand your health risks and when to seek treatment for them.

Here are five medical conditions related to seborrheic dermatitis.

1. Diabetes and Metabolic Syndrome

People with seborrheic dermatitis are more likely to have type 2 diabetes or metabolic syndrome. Metabolic syndrome is a group of conditions that include three or more of the following:

• Hypertension (high blood pressure)
• High blood sugar from insulin resistance or diabetes
• High levels of “bad” cholesterol (particularly low-density lipoprotein, or LDL)
• Low levels of “good” cholesterol (high-density lipoprotein, or HDL)
• A large waist circumference (also called abdominal obesity)

Research has found that seborrheic dermatitis is linked to insulin resistance, hypertension, elevated blood lipid levels, and abdominal obesity. Inflammation and shared inflammatory pathways may be a common link between metabolic syndrome and seborrheic dermatitis. Because of this, people with seborrheic dermatitis may benefit from making healthy lifestyle choices and having regular checkups for conditions associated with insulin resistance.

Scientists have also found that the link between seborrheic dermatitis and obesity might have to do with higher levels of LDL and high blood pressure.

Both seborrheic dermatitis and metabolic conditions can also run in families, which suggests they may share some genetic risk factors.

Because metabolic syndrome and type 2 diabetes are common in many people, it’s important to follow your healthcare provider’s advice and get regular checkups or screenings for these conditions.

2. Parkinson’s Disease

Seborrheic dermatitis is also more common in people with neurological disorders such as stroke or Parkinson’s disease. Between 18 percent and 59 percent of people with Parkinson’s have seborrheic dermatitis. However, having one condition doesn’t cause the other.

Researchers don’t fully understand why people with Parkinson’s and other neurological disorders are more likely to have seborrheic dermatitis, but there are some theories.

Parkinson’s disease affects the autonomic nervous system, which controls bodily functions like heart rate, breathing rate, sweating, and temperature regulation. Similarly, seborrheic dermatitis may be affected by increased sweating.

Both seborrheic dermatitis and Parkinson’s disease might also be influenced by the body’s reaction to Malassezia, a type of yeast that lives naturally on the skin. Studies show that Malassezia yeast may play a role in the development and progression of Parkinson’s. It might also play a role in the development of seborrheic dermatitis.

3. HIV and AIDS

People with HIV or AIDS are much more likely to have seborrheic dermatitis. Studies show that around 35 percent of people with early HIV infection and up to 85 percent of those with AIDS also have seborrheic dermatitis. The reason for this connection isn’t fully understood, but it might be due to the fact that people with HIV or AIDS have a weakened immune system.

HIV affects the body’s immune system by infecting and killing a specific type of immune cell known as CD4-positive T cells, which are needed to fight infections and control yeast on the skin. Seborrheic dermatitis may be influenced by levels of these immune cells and an overall weakened immune system. Without enough of these cells, people with HIV or AIDS may develop a yeast overgrowth, fungal infections, and worse seborrheic dermatitis symptoms.

4. Other Skin Conditions

Seborrheic dermatitis may also raise your risk of other skin diseases. To tell these conditions apart, your dermatologist may do a skin biopsy. This means taking a small sample of skin and checking the cells under a microscope.

Other skin conditions that are more likely with seborrheic dermatitis include:

• Acne
• Alopecia areata (patches of hair loss)
• Folliculitis (infected hair follicles)
• Hidradenitis suppurativa (a long-term inflammatory skin condition)
• Rosacea (discoloration of the skin)

In addition, some people with seborrheic dermatitis also develop psoriasis. When these two conditions appear together, it’s known as sebopsoriasis. Researchers believe sebopsoriasis happens when the immune system reacts abnormally to yeast or other organisms.

Keeping track of your symptoms — and even taking pictures — can help your dermatologist figure out if you have more than one skin condition. You might need a different type of medication or treatment plan to manage both.

5. Mental Health Disorders

Seborrheic dermatitis can also affect your mental health. Around 5 percent of adults have seborrheic dermatitis. Among people with mental health disorders, the prevalence of seborrheic dermatitis is around 16 percent.

Mental health conditions that have been linked to seborrheic dermatitis include:

• Anxiety
• Major depressive disorder
• Bipolar disorder
• Schizophrenia

Inflammation may help explain the connection between seborrheic dermatitis and mental health conditions. Emotional stress and feelings of isolation can also play a role. People with seborrheic dermatitis sometimes develop depression and vice versa, and about 1 in 5 experience symptoms of both. Stress and anxiety can also trigger seborrheic dermatitis flare-ups.

It’s important to care for both your body and your mind. If you’re having trouble mentally or emotionally, talk to your healthcare provider. They can refer you to a therapist or support group. Finding people who understand what you’re going through can make a big difference in how you feel.

Join the Conversation

On MySebDermTeam, people share their experiences with seborrheic dermatitis, get advice, and find support from others who understand.

Do you have other health conditions along with seborrheic dermatitis? Let others know in the comments below.