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? Reasons for worsening in summer and treatment methods
Different causes mean completely different treatments
“Small bumps suddenly appeared on my back in the summer.” “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 often the case that you actually have Malassezia folliculitis, not back acne.
Back acne and Malassezia folliculitis look very similar, but they are completely different conditions with different causes. Therefore, their treatments are also completely different, and using acne treatments for Malassezia folliculitis may not only fail to improve the condition but can even worsen it.
In this article, a doctor from Mona Aoyama Clinic explains the differences, how to distinguish between them, why they worsen in summer, and their respective correct treatment methods.
- Online prescription of treatment medications for back acne and Malassezia folliculitis
- Consultation by sending photos - no clinic visit required, available nationwide
- 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 Cutibacterium acnes | Overgrowth of Malassezia fungi (a type of yeast) |
| Appearance | Comedones (whiteheads/blackheads), red inflammatory acne, large pustules | Small, uniformly sized papules and pustules. Scattered along hair follicles |
| Area of occurrence | Back, face, chest, and other areas with many sebaceous glands | Mainly on the torso such as back, chest, and shoulders. Rarely appears on the face |
| Itchiness | Relatively low | Often itchy (characteristic) |
| Size | Varies in size | Numerous small bumps of uniform size |
| Period of worsening | Year-round (summer with high sebum, puberty) | Peaks in July-August. Fungi thrive in hot, humid conditions |
| Effective treatment | Antibiotics (topical/oral), retinoids, chemical peels, etc. | Antifungal drugs (antibiotics for acne are ineffective) |
⚠️ Most Important: Acne treatment drugs (antibiotics) are ineffective for Malassezia folliculitis. Since the cause is "fungi (yeast)" and not "bacteria," antibiotics have no effect and can sometimes worsen the condition by disrupting the balance of microbes.
Reasons for Worsening in Summer
Reasons back acne increases in summer
- Increased sebum secretion: Rising temperatures and humidity lead to excessive sebum secretion, making pores more likely to clog.
- Pore clogging due to sweat: Sweat mixes with sebum, making pore blockage (comedones) more likely.
- Friction from clothing: Friction from thin, tight-fitting clothes can trigger inflammation.
- Oils from sunscreen: If not removed thoroughly, they can cause pore clogging.
Reasons Malassezia folliculitis rapidly increases in summer
- Hot and humid environment: Malassezia fungi rapidly proliferate in warm and moist conditions.
- Disruption of skin microbiota balance due to sweat: When you sweat, the skin surface environment changes, making fungi more dominant.
- Prolonged dampness: Wetsuits, backpacks, and wearing sports clothing for long periods can be triggers.
- Microbial shift due to oral antibiotics: It can also develop when the balance of resident flora is disrupted while taking antibiotics for another condition.
Key Distinguishing Points - Self-Check
| Check Item | Characteristics of Back Acne | Characteristics of Malassezia Folliculitis |
|---|---|---|
| Itchiness | Not much | Itchy (important clue) |
| Size of bumps | Varies (some can be large) | Uniformly small (around 1-2 mm, consistent) |
| Presence of comedones (white/blackheads) | Often present | Almost no comedones |
| Are there similar symptoms on the face? | Acne often present on the face too | Rarely appears on the face |
| Response to over-the-counter acne care | May improve slightly | Does not improve or may worsen |
| Did it rapidly increase in summer? | May worsen due to increased sebum, but rarely a rapid increase | Often rapidly increases in July-August |
🔍 If you have "itchiness," "uniformly sized bumps," and "a rapid increase in summer," there's a high possibility of Malassezia folliculitis. Accurate diagnosis requires a doctor's examination.
Respective Treatments
Treatment for Back Acne
| Treatment Method | Content |
|---|---|
| Topical antibiotics | Gentamicin, Dalacin T Gel, etc., effective against acne bacteria |
| Topical retinoids | Unclogs pores (comedones) |
| Oral antibiotics | For severe or highly inflamed cases. Minocycline, Doxycycline, etc. |
| Chemical peel | Cleans pores with salicylic acid or glycolic acid. Promotes skin cell turnover. |
Treatment for Malassezia Folliculitis
| Treatment Method | Content |
|---|---|
| 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 promptly, use quick-drying underwear, dry skin quickly after bathing. |
| Antibiotics are NOT recommended | Antibiotics are ineffective as it is not bacterial. Avoid their use. |
Lifestyle Habits for Prevention
- Shower or wipe off sweat immediately: Prolonged sweat on the skin can worsen both conditions.
- Wear quick-drying, breathable innerwear: Preventing dampness is particularly effective in preventing Malassezia folliculitis.
- Re-evaluate how you wash your back: Don't scrub harshly; wash by gently enveloping with lather.
- Prevent shampoo residue: Shampoo running down your back can cause clogging.
- Be careful with Malassezia while taking antibiotics: If you're taking antibiotics for another condition and notice changes on your back, consult a doctor promptly.
Frequently Asked Questions
While there are some general guidelines, an accurate diagnosis requires a doctor's examination (and microscopic examination if necessary). If you have itchiness, numerous uniformly sized bumps, and a rapid increase in summer, suspect Malassezia folliculitis and consult via online medical care.
In Japan, it requires a doctor's prescription. While some over-the-counter dandruff and itch shampoos may contain similar ingredients, the concentration differs. Please consult through online medical care for an appropriate prescription.
Yes, there are cases where both back acne and Malassezia folliculitis coexist on the back. In such cases, treatment that addresses both conditions is necessary. It is recommended to seek a diagnosis rather than self-diagnose.
Malassezia folliculitis may improve when the weather cools. However, if left untreated, it can lead to post-inflammatory hyperpigmentation or recurrences, so early treatment is recommended.
Related Columns
What is Malassezia folliculitis? Can shampoo cure it? A doctor explains the correct treatment Reasons why décolletage and back acne increase in summer – The mechanism of sweat, sebum, and friction
Consultation Hours / Access (Online Consultation)
| Clinic Name | Mona Aoyama Clinic |
| Consultation Format | Online Consultation (Nationwide) / 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 Tokyo Metro "Aoyama-itchome Station" |
| Online Consultation | Available 24 hours / Same-day shipping (for payments made by 4 PM) |
For back acne and Malassezia folliculitis treatment, visit Mona Aoyama Clinic
Consultation by sending photos and online prescriptions are available. You can consult from anywhere in the country.
