What's the difference between back acne and Malassezia folliculitis? Why they worsen in summer, and their treatments
目次
June 11, 2026
What's the Difference Between Back Acne and Malassezia Folliculitis? Why it Worsens in Summer and Treatment Methods
Different causes mean completely different treatments
"Every summer, my back suddenly gets a lot of small bumps," "I've been using acne care products for what I thought was back acne, but it's not getting better at all," "I feel like over-the-counter acne medications are making it worse"—if you've had these experiences, it's not uncommon for it to actually be Malassezia folliculitis instead of back acne.
Back acne and Malassezia folliculitis look very similar, but they are completely different conditions with entirely different causes. Therefore, the treatment methods are also completely different, and using acne-focused treatments for Malassezia folliculitis may not only fail to improve it but could even worsen it.
In this article, a doctor from Mona Aoyama Clinic explains the differences between the two, how to distinguish them, why they increase in summer, and their respective correct treatment methods.
- Online prescription for back acne and Malassezia folliculitis treatments
- Consultation by sending photos—no visit required, nationwide support
- Same-day prescription and same-day shipping (for payments made by 4 PM)
Back Acne vs. Malassezia Folliculitis — Comparison Table
| Comparison Item | Back Acne (Acne Vulgaris) | Malassezia Folliculitis |
|---|---|---|
| Cause | Bacterial inflammation caused by acne bacteria (Cutibacterium acnes) | Overgrowth of Malassezia genus fungi (a type of yeast) |
| Appearance | Comedones (whiteheads/blackheads), red inflammatory acne, large pustules | Small, uniform-sized papules and pustules scattered along hair follicles |
| Location | Areas with many sebaceous glands such as back, face, chest | Mainly trunk such as back, chest, shoulders. Rarely appears on the face |
| Itchiness | Relatively mild | Often itchy (characteristic) |
| Size | Varies in size | Numerous small bumps of uniform size |
| Season for worsening | All year round (summer with high sebum, puberty) | Peaks in July-August. Fungi proliferate easily in hot and humid conditions |
| Effective Treatment | Antibiotics (topical/oral), retinoids, chemical peels, etc. | Antifungal drugs (acne-targeted antibiotics are ineffective) |
⚠️ Most Important: Acne treatments (antibiotics) are ineffective for Malassezia folliculitis. Since the cause is "fungus (yeast)" not "bacteria," antibiotics have no effect and can even worsen the condition by disturbing the bacterial balance.
Reasons for Worsening in Summer
Reasons Back Acne Increases in Summer
- Increased Sebum Secretion: Rising temperatures and humidity cause excessive sebum secretion, leading to clogged pores.
- Sweat Clogging Pores: Sweat mixes with sebum, making pore blockage (comedones) more likely.
- Friction from Clothing: Friction from thin, tight clothing can trigger inflammation.
- Oily Sunscreen: If not regularly removed, it can cause clogged pores.
Reasons Malassezia Folliculitis Surges in Summer
- Hot and Humid Environment: Malassezia fungi rapidly proliferate in warm, moist conditions.
- Disruption of Skin Microbiome by Sweat: Sweating changes the skin's surface environment, allowing fungi to become dominant.
- Prolonged Stuffiness: Wetsuits, backpacks, and prolonged wear of sports apparel can be triggers.
- Bacterial Shift Due to Oral Antibiotics: Can also occur when taking antibiotics for another condition, disturbing the normal bacterial balance.
Key Distinguishing Points — Self-Check
| Check Item | Characteristics of Back Acne | Characteristics of Malassezia Folliculitis |
|---|---|---|
| Itchiness | Rarely itchy | Itchy (important clue) |
| Size of Bumps | Varied (some can be large) | Uniformly small (around 1-2mm, consistent size) |
| Presence of Comedones (white/blackheads) | Often present | Comedones are almost never present |
| Similar symptoms on face? | Acne often appears on the face as well | Rarely appears on the face |
| Response to OTC acne care | May show some improvement | Does not improve / May worsen |
| Sudden increase in summer? | Worsens due to increased sebum, but rarely a sudden surge | Often surges in July-August |
🔍 If you have "itchiness," "uniform size," and "sudden increase in summer," there's a high possibility it's Malassezia folliculitis. Accurate diagnosis requires a doctor's examination.
Treatment Methods for Each
Back Acne Treatment
| Treatment Method | Description |
|---|---|
| Topical Antibiotics | Gentamicin, Dalacin T gel, etc. Effective against acne bacteria. |
| Topical Retinoids | Clears clogged pores (comedones). |
| Oral Antibiotics | For severe cases or strong inflammation. Minocycline, Doxycycline, etc. |
| Chemical Peel | Salicylic acid, glycolic acid to cleanse pores. Promotes skin cell turnover. |
Malassezia Folliculitis Treatment
| Treatment Method | Description |
|---|---|
| Antifungal drugs (topical) | Ketoconazole shampoo, cream, etc. Directly eliminates fungi. |
| Antifungal drugs (oral) | For severe or widespread cases. Itraconazole, etc., are prescribed. |
| Lifestyle improvements | Wipe away sweat frequently, use quick-drying innerwear, dry quickly after bathing. |
| Antibiotics are NOT recommended | Ineffective as it's not bacterial. Avoid use. |
Lifestyle Habits for Prevention
- Shower or wipe off sweat immediately: Prolonged sweat can exacerbate both conditions.
- Wear quick-drying, breathable innerwear: Preventing stuffiness is particularly effective in preventing Malassezia folliculitis.
- Review how you wash your back: Don't scrub vigorously; wash by enveloping with foam.
- Prevent shampoo residue: Shampoo running down your back can cause blockages.
- Be careful of Malassezia during antibiotic treatment: If you're taking antibiotics for another condition and notice changes on your back, consult a doctor early.
Frequently Asked Questions
While there are some guidelines, an accurate diagnosis requires a doctor's examination (and microscopic examination if necessary). If you experience itchiness, numerous uniform small bumps, and a sudden increase in summer, suspect Malassezia folliculitis and consult us via online consultation.
In Japan, it requires a doctor's prescription (prescription medication). While there are over-the-counter anti-dandruff and anti-itch shampoos with similar ingredients, their concentrations differ. Please consult us via online consultation for an appropriate prescription.
Yes, it's possible. There are cases where both back acne and Malassezia folliculitis are present on the back, requiring treatment that addresses both. It's better to get a medical examination than to self-diagnose.
Malassezia folliculitis may improve when the weather cools down. However, leaving it untreated can lead to post-inflammatory hyperpigmentation or recurrence, so early treatment is recommended.
Related Columns
What is Malassezia Folliculitis? Can Shampoo Cure It? A Doctor Explains the Correct Treatment Why Decollete and Back Acne Increase in Summer — The Mechanism of Sweat, Sebum, and FrictionConsultation Hours / Access (Online Consultation)
| Clinic Name | Mona Aoyama Clinic |
| Consultation Format | Online Consultation (Nationwide Support) / In-person Consultation (Aoyama, Tokyo) |
| Location | 3F D Building, 1-10-3 Minami-Aoyama, Minato-ku, Tokyo 107-0062 |
| Nearest Station | 5-minute walk from "Aoyama-itchome Station" on Tokyo Metro |
| Online Consultation | 24-hour reception / Same-day shipping available (for payments made by 4 PM) |
For treatment of back acne and Malassezia folliculitis, visit Mona Aoyama Clinic.
Consultation by sending photos and online prescriptions available. You can consult us from anywhere in the country.