Immune Response: The body’s defense mechanism against harmful invaders, which can include pathogens, allergens, or irritants. In skincare, a compromised immune response can result in conditions like eczema, dermatitis, or allergic reactions.

Immunosuppressants: Medications or treatments that suppress the immune system, often used to treat autoimmune diseases or prevent organ rejection. They can affect skin health by increasing the risk of infections or causing skin thinning.

Indian Ginseng: An adaptogenic herb known for its antioxidant and anti-inflammatory properties, often used in skincare to promote skin health, reduce stress, and protect against environmental damage.

Indigo Extract: A plant extract known for its calming, anti-inflammatory, and antibacterial properties, often used in skincare to soothe irritated skin and treat conditions like acne or eczema.

Infrared Light: A type of light therapy used in certain skincare treatments to stimulate collagen production, reduce inflammation, and improve blood circulation. It can penetrate deeper into the skin compared to visible light.

Ingestible Skincare: Supplements or products designed to be consumed orally to support skin health from the inside out. These can include vitamins, minerals, collagen peptides, and antioxidants.

Intensive Care: Skincare products or treatments designed to address severe skin issues or provide deep hydration, nourishment, or healing. These are typically more potent than regular products and are intended for specific skin concerns like deep wrinkles, scars, or extreme dryness.

In vitro: A term used to describe experiments or processes conducted outside of a living organism, typically in a controlled laboratory environment, such as testing the efficacy of skincare ingredients on cells or tissues.

Iontophoresis: A non-invasive treatment technique that uses electrical currents to drive active ingredients, like serums or medications, into the skin. It is commonly used in professional skincare treatments to enhance the absorption of certain ingredients.

Irritable Skin Syndrome: A condition characterized by heightened sensitivity and reactivity of the skin. This can result in redness, itching, or a stinging sensation, often triggered by harsh products, environmental factors, or stress.

Irritant: A substance that causes discomfort, inflammation, or a reaction when it comes in contact with the skin. Irritants can cause redness, burning, itching, or dryness, and are often found in harsh chemicals or fragrances in skincare products.

Isopropyl Alcohol: A type of alcohol commonly used in skincare products for its antiseptic and solvent properties. It can be drying to the skin and is often found in toners or products meant for acne treatment, but excessive use can lead to irritation.

Isopropyl Myristate: An ester used in skincare products as a solvent and penetration enhancer. It helps other ingredients absorb better into the skin but can sometimes cause irritation in sensitive individuals.

Isotretinoin: A potent oral medication used to treat severe acne, particularly cystic acne. It works by reducing sebum production and decreasing the size of sebaceous glands, but it may have significant side effects, including dry skin and irritation.