Are Nightshades Triggering Your Eczema? Here’s What You Need to Know

For those living with eczema, managing flare-ups can be a constant challenge, and identifying potential triggers is crucial for controlling symptoms. While common food allergens like dairy, gluten, or soy often receive the most attention, nightshade vegetables—such as tomatoes, potatoes, peppers, and aubergines—are lesser-known but significant potential triggers that may exacerbate skin conditions like eczema. These vegetables, although rich in essential nutrients, contain naturally occurring compounds that may induce inflammation in sensitive individuals.

If you have tried various dietary changes and your eczema symptoms persist, it’s worth considering whether nightshades are playing a role in your condition. This article dives deeper into how nightshades might impact skin health, particularly for individuals prone to eczema, and offers practical advice on how to approach potential sensitivities.

Today’s article is going to cover: 

• What are nightshades? 
• How Nightshades Contribute to Inflammation
  • Alkaloids
  • Lectins and Atopic Dermatitis
  • Saponins and Skin Barrier Disruption
• Why Nightshades Are Particularly Problematic for Atopic and Contact Dermatitis
  • Atopic dermatitis and nightshades
  • Contact dermatitis and nightshades
• Signs That Nightshades May Be Triggering Your Eczema
• What to Eat Instead of Nightshades

What Are Nightshades?

Nightshades are part of the *Solanaceae* family, comprising over 2,000 species of plants, including several commonly consumed vegetables:

• Tomatoes
• Potatoes (excluding sweet potatoes)
• Peppers (bell peppers, chilli peppers, and paprika)
• Aubergines
• Goji berries
• Tomatillos

How Nightshades Contribute to Inflammation

These vegetables are known for their dense nutritional profiles, offering a wealth of vitamins, minerals, and antioxidants. However, nightshades also contain bioactive compounds such as alkaloids, lectins, and saponins, which can exacerbate inflammation in susceptible individuals. This is particularly concerning for those with eczema (atopic dermatitis) and contact dermatitis, who may already have heightened immune responses and skin sensitivities.

The inflammatory potential of nightshades lies in their bioactive compounds, particularly alkaloids, lectins, and saponins, which can disrupt immune regulation and gut health. For people with dermatitis—especially atopic and contact dermatitis—these compounds may heighten immune reactivity, leading to flare-ups.

Alkaloids

Among the various compounds present in nightshades, alkaloids are of particular concern when it comes to inflammatory conditions like eczema. Glycoalkaloids(1) are nitrogen-containing chemicals that can affect nerve function and gastrointestinal health. For eczema sufferers, compromised gut health or an overactive immune system can trigger skin flare-ups, and alkaloids may aggravate these responses. Let’s look at the primary compounds found in nightshades:

Solanine and Atopic Dermatitis

Solanine, found in white potatoes and tomatoes, is a glycoalkaloid that can irritate the gut lining and increase intestinal permeability, often referred to as “leaky gut.” Research suggests that gut health plays a crucial role in inflammatory skin conditions, including atopic dermatitis. When solanine compromises the gut barrier, toxins and inflammatory molecules may enter the bloodstream and reach the skin, provoking an immune response that manifests as inflammation, itching, and worsening eczema. (2)

For those with atopic dermatitis, this inflammatory cascade can aggravate the skin’s barrier function, which is already impaired. Solanine has also been found to inhibit acetylcholinesterase, an enzyme involved in nerve function, potentially increasing skin sensitivity and worsening itch in atopic dermatitis sufferers.
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Capsaicin and Contact Dermatitis

Capsaicin, the compound responsible for the spiciness of chilli peppers, has a well-documented effect on sensory nerves and inflammatory pathways. While capsaicin is often used topically for its analgesic properties, oral consumption or contact with capsaicin-containing foods can trigger skin irritation in some individuals. People with contact dermatitis may experience a flare-up of symptoms when consuming spicy foods, particularly if their skin is already sensitised to environmental triggers.

In addition, capsaicin is known to activate TRPV1 receptors in the skin, which are responsible for heat and pain sensation. Overstimulation of these receptors may worsen inflammatory responses in people with contact dermatitis, causing heightened skin irritation, redness, and burning sensations. (3)

Nicotine and Immune Dysregulation

Nicotine, present in small amounts in nightshades like tomatoes and potatoes, can interfere with immune system function. While the nicotine content in these vegetables is low, it may still have an impact on people with hypersensitive immune systems, such as those with atopic dermatitis. Nicotine is known to stimulate the release of both anti and pro-inflammatory cytokines, which can exacerbate immune-driven skin conditions.

For individuals with atopic dermatitis, which is characterised by an overactive immune system, the introduction of even small amounts of nicotine may further amplify immune dysregulation, leading to increased inflammation and skin barrier dysfunction.

Lectins and Atopic Dermatitis

Lectins are proteins that bind to carbohydrates and are present in many foods, including nightshades. In excess, lectins may irritate the gut lining and promote inflammation. Lectins in tomatoes and potatoes have been shown to affect gut permeability and may trigger immune responses, contributing to the inflammatory cascade involved in atopic dermatitis.

Atopic dermatitis is often associated with gut dysbiosis and increased intestinal permeability, which allows inflammatory molecules to pass through the gut lining and circulate within the body. Once in the bloodstream, these molecules can cause inflammation that can worsen skin conditions like eczema. 

Saponins and Skin Barrier Disruption

Saponins, found in nightshades such as tomatoes, potatoes, and aubergines, have foaming or soap-like, properties that can disrupt cell membranes. This disruption can occur both in the gut and the skin, where saponins may compromise the protective barrier function. In people with eczema or contact dermatitis, where the skin barrier is already weakened, saponins may exacerbate irritation by making the skin more susceptible to environmental allergens, irritants, and microbial invasion.

Furthermore, saponins are known to provoke an immune response by activating immune cells in the gut, which can lead to a systemic inflammatory reaction. In susceptible individuals, this inflammatory cascade can manifest as heightened eczema or dermatitis symptoms, including increased itching, redness, and dryness.

Why Nightshades Are Particularly Problematic for Atopic and Contact Dermatitis

Eczema is characterised by chronic skin inflammation, often related to an overactive immune system. For those with eczema, the immune system tends to overreact to harmless substances, causing a cascade of inflammatory responses that result in skin irritation, itching, and dryness. Because nightshades contain compounds that can promote inflammation or irritate the immune and digestive systems, they have the potential to worsen eczema symptoms.

One of the key reasons nightshades may trigger eczema is through their effect on the gut-skin axis. The health of the gut plays a crucial role in maintaining skin health. A compromised gut lining, often referred to as “leaky gut,” can allow toxins and inflammatory molecules to enter the bloodstream, which can then manifest as skin irritation or inflammation. This connection is particularly relevant for eczema sufferers, as research indicates that those with eczema often experience gut dysbiosis—an imbalance in the gut microbiome.

Additionally, some individuals may have a genetic predisposition that makes them more sensitive to nightshades. This could be due to variations in how their body metabolises alkaloids, lectins, or other compounds, resulting in a stronger inflammatory response.

Atopic Dermatitis and Nightshades

Atopic dermatitis is an immune-driven condition where the skin’s barrier function is impaired, leading to dry, itchy, and inflamed skin. The overactive immune system reacts to environmental triggers, allergens, and potentially certain foods. Since nightshades contain compounds that can promote gut permeability and trigger immune responses, they are especially concerning for people with atopic dermatitis. 

The gut-skin axis plays a key role here: increased intestinal permeability caused by compounds like solanine, lectins, and saponins can exacerbate systemic inflammation, which then manifests in the skin.

Research has shown that individuals with atopic dermatitis often have higher levels of systemic inflammation and may be more reactive to food triggers. Nightshades, due to their inflammatory potential, may worsen this immune dysregulation, leading to more frequent and severe eczema flare-ups.

Contact Dermatitis and Nightshades

Contact dermatitis, an inflammatory skin condition caused by direct contact with allergens or irritants, can also be worsened by nightshades. While contact dermatitis is typically triggered by touch, eating nightshades—especially capsaicin-containing foods—can also irritate the skin. Capsaicin’s activation of TRPV1 receptors may make the skin more sensitive to environmental triggers, leading to more pronounced symptoms.

In people with contact dermatitis, the inflammatory response triggered by alkaloids, lectins, and saponins can amplify skin irritation, especially when combined with exposure to environmental irritants or allergens.

Signs That Nightshades May Be Triggering Your Eczema

Determining whether nightshades are triggering your eczema can be tricky, but there are some common signs to watch for:

• Increased Eczema Flare-ups: If your eczema consistently worsens after consuming nightshades like tomatoes, potatoes, or peppers, these foods may be a trigger for you.
• Timing of Symptoms: Symptoms may not appear immediately after eating nightshades, but may surface within hours or even days, complicating the identification of triggers. It’s important to monitor your eczema closely after consuming these foods.
• Additional Inflammatory Symptoms: In addition to skin irritation, you may notice other signs of inflammation, such as joint pain, muscle stiffness, or digestive upset, after eating nightshades. These symptoms may suggest a systemic inflammatory response.
• Track Your Symptoms: Keep a food and symptom diary to observe any correlations between nightshade consumption and flare-ups. Note any changes in skin irritation, itching, or redness following the consumption of nightshade vegetables. Here’s a link to my free Food and Symptom Diary
• Elimination Diet: Eliminate all nightshades from your diet for a minimum of four weeks to see if your symptoms improve. Foods to avoid include tomatoes, potatoes, peppers, aubergines, and nightshade-derived ingredients like paprika and certain sauces.
• Reintroduction: After the elimination period, gradually reintroduce nightshade vegetables one at a time, spacing each reintroduction by several days. This will help you identify specific triggers and monitor whether your skin condition worsens—

What to Eat Instead of Nightshades

If nightshades are found to be a trigger for your eczema, there are plenty of nutritious alternatives to maintain a balanced diet:

• Sweet Potatoes: A great alternative to regular potatoes, sweet potatoes are rich in beta-carotene and other vitamins, without the inflammatory alkaloids found in nightshades.
• Leafy Greens: Kale, spinach, and Swiss chard can replace tomatoes and peppers in salads, soups, and stir-fries.
• Spices: Instead of nightshade-based spices like paprika or chilli, opt for anti-inflammatory spices like turmeric, ginger, cumin, and cinnamon to add flavour to your dishes without triggering inflammation.

While nightshades are not problematic for everyone, they can exacerbate symptoms for some eczema sufferers due to their alkaloid content and inflammatory potential. If you’ve struggled to manage your eczema despite trying other dietary changes, eliminating nightshades could be an effective strategy. 

It’s important to consult a healthcare professional or Registered Nutritional Therapist before making significant changes to your diet to ensure you’re meeting all your nutritional needs while managing your eczema effectively.

By paying close attention to your diet, tracking your symptoms, and identifying potential food triggers like nightshades, you can take important steps towards clearer, healthier skin. address the issue through diet.

REFERENCES

1. Ahamad J, Uthirapathy S, Anwer ET, Naim MohdJ, Mir SR. Glycoalkaloids as Food Toxins. In: Analysis of Naturally Occurring Food Toxins of Plant Origin. CRC Press; 2022. p. 81–94. 
2. Keuter L, Wolbeck A, Kasimir M, Schürmann L, Behrens M, Humpf HU. Structural Impact of Steroidal Glycoalkaloids: Barrier Integrity, Permeability, Metabolism, and Uptake in Intestinal Cells. Mol Nutr Food Res. 2024 Mar 1;68(6). 
3. Barker C, Elston DM. Botanical Briefs: Handling the Heat From Capsicum Peppers. Cutis. 2023 May 1;111(5):241–3.