Acne: Types, Causes, Treatments, and the Functional Medicine Approach

Acne is the most common skin condition on the planet. It affects roughly 50 million Americans every year and shows up in nearly every culture across the globe. Yet despite how common it is, acne remains wildly misunderstood.

Most people think acne is a teenage problem caused by dirty skin. That is wrong on both counts. Acne can strike at any age, and it has almost nothing to do with hygiene. It is a complex inflammatory condition driven by hormones, genetics, gut health, diet, and immune function.

This guide covers everything you need to know: what acne actually is, why it happens, the different types you might be dealing with, every treatment option from conventional to advanced regenerative medicine, and when you should see a specialist. Whether you are a teenager dealing with your first breakout or an adult wondering why you still get pimples at 35, this is your complete resource.

What Is Acne, Really? The Pathophysiology Explained

Acne (acne vulgaris) is a chronic inflammatory disease of the pilosebaceous unit. That is the technical name for the structure that includes your hair follicle and its attached sebaceous (oil) gland.

Here is how the process unfolds, step by step:

Step 1: Excess Sebum Production

Your sebaceous glands produce an oily substance called sebum. Sebum is not inherently bad. It keeps your skin moisturized and protected. But when your glands go into overdrive, usually triggered by androgens (male hormones that both men and women produce), you end up with too much oil clogging the works.

Step 2: Follicular Hyperkeratinization

Normally, dead skin cells shed from the lining of your pores and get pushed to the surface. In acne-prone skin, these cells become sticky and clump together, forming a plug called a microcomedone. This is the invisible seed of every pimple.

Step 3: Bacterial Colonization

Cutibacterium acnes (formerly called Propionibacterium acnes, or P. acnes) is a bacterium that naturally lives in your pores. It feeds on sebum. When a pore gets clogged and fills with oil, C. acnes has an all-you-can-eat buffet. The bacterial population explodes.

Step 4: The Inflammatory Cascade

Your immune system detects the bacterial overgrowth and sends in inflammatory cells. These immune cells release cytokines, enzymes, and free radicals that damage the follicular wall. The result: redness, swelling, pus, and pain. If the inflammation goes deep enough, it destroys tissue and causes scarring.

The 5 Types of Acne You Need to Know

Not all acne is created equal. The type you have determines the treatment that will work best.

1. Comedonal Acne

This is the mildest form. It shows up as blackheads (open comedones) and whiteheads (closed comedones). There is little to no inflammation. You will not see redness or swelling. Comedonal acne responds well to topical retinoids and salicylic acid.

2. Inflammatory Acne

Red, swollen papules and pustules. This is what most people picture when they think of acne. The bumps are tender to the touch and can leave behind red or brown marks (post-inflammatory hyperpigmentation). Benzoyl peroxide, retinoids, and sometimes topical antibiotics are first-line treatments.

3. Cystic/Nodulocystic Acne

The most severe form. Deep, painful nodules and cysts that sit under the skin for weeks. Cystic acne carries the highest risk of permanent scarring. It almost always requires prescription treatment, and isotretinoin (Accutane) is often the only thing that provides lasting clearance.

4. Hormonal Acne

Typically appears along the jawline, chin, and lower cheeks. It flares with menstrual cycles, is common in women with PCOS (polycystic ovary syndrome), and often persists into the 20s, 30s, and beyond. Hormonal acne in women may respond to spironolactone, oral contraceptives, or addressing underlying hormonal imbalances.

5. Fungal Acne (Malassezia Folliculitis)

This is technically not acne at all. It is caused by an overgrowth of Malassezia yeast in hair follicles. It looks like small, uniform, itchy bumps, usually on the forehead, chest, or upper back. The giveaway: it itches (true acne usually does not), and it does not respond to standard acne treatments. Antifungal medications clear it up.

Acne Grading Systems

Dermatologists use grading systems to classify acne severity and guide treatment decisions. The two most commonly used are:

The Global Acne Grading System (GAGS): Scores acne by location and lesion type. Each area of the face and body receives a factor score multiplied by the most severe lesion type present. Total scores range from 0 (clear) to 44 (very severe).

The Leeds Revised Scale: Uses photographic comparison to grade inflammatory acne from 1 to 12, with separate grading for the face, chest, and back.

The Simplified Classification Most Doctors Use:

• Mild: Mostly comedones, few papules, no nodules
• Moderate: Mix of comedones, papules, and pustules; some scarring risk
• Severe: Numerous inflammatory lesions, nodules and/or cysts, active scarring

Knowing your grade helps determine whether you need over-the-counter products, prescription topicals, systemic medications, or a combination approach.

Causes and Triggers: Why You Break Out

Acne has a genetic foundation. If both your parents had acne, you have a roughly 80% chance of developing it. But genes load the gun. Environment and lifestyle pull the trigger.

Hormones

Androgens (testosterone, DHEA-S, DHT) are the primary hormonal drivers. They increase sebum production and promote follicular plugging. This is why acne peaks during puberty and why women often break out before their periods, during pregnancy, or with conditions like PCOS. Insulin and IGF-1 (insulin-like growth factor) also play a role by stimulating androgen production and sebaceous gland activity.

Diet

The connection between food and acne was dismissed for decades. The research now tells a different story:

• High-glycemic foods (white bread, sugar, processed carbs) spike insulin and IGF-1, which ramp up sebum production. Multiple controlled studies link high-glycemic diets to increased acne severity.
• Dairy (especially skim milk) contains hormones and bioactive molecules that may worsen acne. The association is moderate but consistent across several large observational studies.
• Whey protein supplements are a common trigger, particularly in athletes. Whey spikes insulin and contains growth factors that stimulate sebaceous glands.
• Chocolate: The evidence is mixed. Some small studies suggest cocoa itself may increase inflammatory lesions, but the sugar and dairy in most chocolate products are likely the bigger issue.

Stress

Chronic stress raises cortisol, which increases sebum production and impairs wound healing. College students consistently show acne flares during exam periods. Stress also disrupts the gut microbiome, creating another pathway to skin inflammation (more on this below).

Medications

Several drugs can cause or worsen acne:

• Corticosteroids (“steroid acne” is very real)
• Lithium
• Androgenic steroids and testosterone therapy
• Some anticonvulsants
• B vitamins (particularly B6 and B12 in high doses)
• Certain progestins in hormonal contraceptives

Skincare and Environmental Factors

Comedogenic (pore-clogging) products are a real issue, especially heavy foundations, coconut oil, and certain sunscreens. Friction from helmets, phones, or face masks (“maskne”) can worsen acne in those areas. Humidity and sweating contribute by creating a breeding ground for bacteria and yeast.

Conventional Treatments: The Standard Playbook

These are the treatments you will find in every dermatology textbook. They work, and they are backed by decades of research.

Topical Treatments

Benzoyl Peroxide (BPO)

Evidence: Strong

Benzoyl peroxide kills C. acnes bacteria through oxidation. Unlike antibiotics, bacteria cannot develop resistance to BPO. Available in concentrations from 2.5% to 10%. Research shows 2.5% is just as effective as 10% with far less irritation. Use it as a wash or leave-on treatment. It bleaches fabrics, so white pillowcases and towels are your friend.

Retinoids (Tretinoin, Adapalene, Tazarotene)

Evidence: Strong

Retinoids are the backbone of acne treatment. They normalize skin cell turnover, prevent follicular plugging, reduce inflammation, and even help fade post-inflammatory marks. Adapalene (Differin) 0.1% is now available over the counter. Tretinoin and tazarotene require a prescription. Start slow (every other night or even every third night) and expect a “purging” period of 4 to 6 weeks where acne temporarily worsens before improving.

Topical Antibiotics

Evidence: Moderate

Clindamycin and erythromycin are the most common topical antibiotics for acne. They reduce C. acnes and have anti-inflammatory effects. The catch: they should NEVER be used alone due to the risk of antibiotic resistance. Always combine with benzoyl peroxide. Combination products like clindamycin/BPO gel simplify this.

Azelaic Acid

Evidence: Strong

An underrated gem. Azelaic acid (15% to 20%) is antibacterial, anti-inflammatory, and helps fade hyperpigmentation. It is safe during pregnancy (a rarity among acne medications) and works well for both acne and rosacea. It can cause mild tingling initially.

Salicylic Acid

Evidence: Moderate

A beta-hydroxy acid (BHA) that penetrates oily pores and dissolves the “glue” holding dead skin cells together. Best for comedonal acne and blackheads. Available in 0.5% to 2% OTC products. Less potent than retinoids but better tolerated.

Systemic Treatments

Oral Antibiotics

Evidence: Strong

Doxycycline and minocycline are the most prescribed oral antibiotics for moderate-to-severe inflammatory acne. They work quickly (usually within 4 to 6 weeks) but should be limited to 3 to 4 months to minimize antibiotic resistance and gut microbiome disruption. Always use alongside topical retinoids and BPO.

Isotretinoin (Accutane)

Evidence: Strong

The closest thing to an acne cure. Isotretinoin shrinks sebaceous glands by up to 90%, normalizes skin cell shedding, reduces C. acnes, and calms inflammation. A typical 5- to 6-month course produces long-term remission in about 85% of patients.

The downsides are real: mandatory pregnancy prevention (isotretinoin causes severe birth defects), monthly blood tests, dry skin and lips, potential mood changes (the depression link is debated but should be monitored), and possible musculoskeletal effects. Despite the side effect profile, isotretinoin remains the single most effective treatment for severe or treatment-resistant acne.

Spironolactone (For Hormonal Acne in Women)

Evidence: Strong

Spironolactone is a blood pressure medication that also blocks androgen receptors. At doses of 50 to 200 mg daily, it is highly effective for hormonal acne in women. Results typically appear within 3 months. Side effects can include increased urination, breast tenderness, irregular periods, and elevated potassium. It should not be used in men or during pregnancy.

Oral Contraceptives

Evidence: Strong

Combined oral contraceptives containing estrogen and a non-androgenic progestin can significantly improve acne in women. They work by reducing free testosterone and decreasing sebum production. Three to four months of consistent use is needed to see results. They are particularly effective when combined with spironolactone for stubborn hormonal acne.

The Regenerative and Functional Medicine Approach

Conventional dermatology is effective. But it often treats acne as a purely skin-level problem. Functional and regenerative medicine asks a different question: what is happening inside the body that is showing up on the skin?

This is not about replacing proven treatments. It is about adding deeper layers of investigation and healing.

The Gut-Skin Axis

Evidence: Emerging

The connection between gut health and skin health is one of the most exciting areas of research in dermatology. Here is what we know:

• People with acne are more likely to have altered gut microbiome composition compared to people with clear skin.
• Small intestinal bacterial overgrowth (SIBO) is significantly more common in acne patients.
• Intestinal permeability (“leaky gut”) may allow bacterial endotoxins into the bloodstream, triggering systemic inflammation that shows up on the skin.
• A 2023 meta-analysis found that probiotic supplementation reduced acne lesion counts in multiple randomized controlled trials.

Functional practitioners often start with a detailed stool analysis to evaluate the microbiome, check for dysbiosis, and look for markers of intestinal inflammation. Treating gut issues, whether that is SIBO, dysbiosis, food sensitivities, or impaired digestion, can produce significant skin improvements.

Food Sensitivity Testing and Elimination Diets

Evidence: Emerging

Beyond dairy and high-glycemic foods, some individuals have specific food sensitivities that trigger or worsen acne through immune-mediated inflammation. Common culprits include gluten, eggs, soy, and certain nuts.

Functional practitioners may use IgG food sensitivity testing as a starting point, though the gold standard remains a structured elimination diet: remove suspect foods for 4 to 6 weeks, then reintroduce them one at a time while tracking skin changes. This approach requires patience but can uncover hidden triggers that no topical product will fix.

Red Light and Blue Light Therapy

Evidence: Moderate

Light-based therapies offer a drug-free approach to acne management:

• Blue light (415 nm): Kills C. acnes bacteria by activating porphyrins (light-sensitive molecules) within the bacteria. Most effective for mild to moderate inflammatory acne. In-office treatments show better results than home devices due to higher intensity.
• Red light (630 to 660 nm): Reduces inflammation and promotes tissue repair. Less antibacterial than blue light, but better for calming active inflammation and supporting healing.
• Combination red/blue light: Several studies show this outperforms either wavelength alone. A 2019 systematic review found combination LED therapy reduced inflammatory lesions by 46% to 77% over 4 to 8 weeks.

Home LED devices have become popular. They can help maintain results, but manage expectations: at-home devices are significantly less powerful than clinical-grade units. For moderate to severe acne, professional treatments will deliver better outcomes.

Additional Functional Approaches

Vitamin D optimization: Low vitamin D is associated with increased acne severity in multiple studies. Testing and supplementing to reach 40 to 60 ng/mL is reasonable.
Berberine: A plant compound that improves insulin sensitivity and has antimicrobial properties. Some practitioners use it as a natural alternative for metabolic-driven acne.
DIM (Diindolylmethane): Derived from cruciferous vegetables, DIM supports healthy estrogen metabolism and may help with hormonally-driven breakouts.
Spearmint tea: Two cups daily has been shown to reduce free testosterone in women, with some studies showing improvement in hormonal acne. A gentle option worth trying.

Acne Scarring: Types and Treatment Options

Even after active acne clears, the scars can linger for years or a lifetime. Understanding scar types is critical because each responds to different treatments.

Types of Acne Scars

• Ice pick scars: Deep, narrow, pitted scars that extend into the dermis. The most difficult to treat.
• Boxcar scars: Broad, rectangular depressions with sharp edges. Respond well to resurfacing.
• Rolling scars: Wide, shallow depressions with smooth, undulating borders. Caused by fibrous bands tethering the skin.
• Hypertrophic/keloid scars: Raised, thickened scars from excess collagen production. More common on the chest, back, and jawline.
• Post-inflammatory hyperpigmentation (PIH): Not true scars, but dark marks left behind after a pimple heals. These fade with time and topical treatment.
• Post-inflammatory erythema (PIE): Red or purple marks from damaged blood vessels. Common in lighter skin tones. Pulsed dye laser and time are the best treatments.

Regenerative Scar Treatments

PRP (Platelet-Rich Plasma) for Acne Scars

PRP deserves special attention in any discussion of regenerative approaches to scarring. The treatment involves drawing a small amount of your blood, spinning it in a centrifuge to concentrate the platelets and growth factors, and then applying or injecting the PRP into scarred areas.

Multiple randomized controlled trials have shown that microneedling combined with PRP produces significantly better scar improvement than microneedling alone. The growth factors in PRP (PDGF, TGF-beta, VEGF) stimulate collagen remodeling, angiogenesis, and tissue regeneration. A 2021 systematic review and meta-analysis confirmed that adding PRP to microneedling improved scar outcomes by an additional 20% to 30% compared to microneedling with saline.

Sessions are typically spaced 4 to 6 weeks apart. Most patients need 3 to 4 sessions for optimal results. Downtime is minimal: redness for 24 to 48 hours, with full recovery within a few days.

Microneedling for Acne Scars

Microneedling (also called collagen induction therapy) uses tiny needles to create controlled micro-injuries in the skin. This triggers your body’s wound-healing cascade, producing new collagen and elastin that fills in and smooths out scars.

Professional microneedling devices use needle depths of 1.0 to 2.5 mm for acne scars. Home dermarollers (0.25 to 0.5 mm) can help with product absorption and mild texture improvement, but they do not reach deep enough to remodel scar tissue. For real scar revision, you need a professional setting.

Results are cumulative. You will see gradual improvement over 3 to 6 months as new collagen matures. Combining microneedling with PRP, growth factor serums, or radiofrequency energy can enhance results.

When to See a Dermatologist

Self-treatment is reasonable for mild acne. But there are clear situations where professional help is needed:

• Your acne is leaving scars. Scarring means tissue destruction is happening now. Do not wait.
• Over-the-counter treatments have not worked after 8 to 12 weeks. You have given them a fair shot. Time to escalate.
• You have deep, painful nodules or cysts. These require prescription treatment and sometimes cortisone injections for acute flares.
• Your acne is affecting your mental health. Acne-related depression and anxiety are real and common. You deserve help.
• You suspect hormonal acne. Blood work can identify hormonal imbalances, and targeted treatment can make a dramatic difference.
• Your acne appeared suddenly in adulthood. New-onset adult acne can signal hormonal changes, medication side effects, or other medical conditions worth investigating.

A good dermatologist will assess your acne type and severity, discuss your history and goals, and build a treatment plan that may include topicals, systemic medications, procedures, or referral for functional evaluation. If your current provider only offers topical prescriptions and does not discuss lifestyle factors, consider seeking a practitioner who takes a more detailed approach.

Frequently Asked Questions

The Bottom Line

Acne is complex, but it is treatable. The key is matching your treatment to your specific type of acne, your triggers, and your goals.

For mild acne, a simple routine of retinoid plus benzoyl peroxide clears most people. For moderate inflammatory acne, adding a short course of oral antibiotics or switching to a combination approach accelerates results. For hormonal acne in women, spironolactone is significant. For severe cystic acne, isotretinoin remains the gold standard.

And for anyone interested in a deeper approach, functional medicine offers valuable tools: gut health optimization, targeted supplementation with zinc and omega-3s, dietary modification, and advanced regenerative treatments like PRP and light therapy.

The worst thing you can do is nothing. Untreated acne causes unnecessary scarring and significant psychological harm. Whether you start with over-the-counter products or go straight to a dermatologist, take action. Your future self will thank you.

This article is for informational purposes only and does not constitute medical advice. Always consult with a qualified healthcare provider before starting any new treatment.

Related Reading

• Ehlers-Danlos Syndrome: Diagnostic Criteria, Types, and What the 2026 Updates Mean for You
• Leaky Gut Syndrome: What the Research Actually Says
• PRP Therapy: How Platelet-Rich Plasma Works and What It Treats
• SIBO (Small Intestinal Bacterial Overgrowth): Types, Testing, Treatment, and Why It Keeps Coming Back