Pimples are inflamed comedones and a part of acne vulgaris. Comedones occur after the proliferation of cells lining the sebaceous duct (cornification) and an increase in sebum production (seborrhea), primarily owing to the hypersensitivity of pilosebaceous units to circulating androgens (e.g., testosterone). Increased comedones inflammation occurs due to the rise in sebum production, colonization with Cutibacterium acnes and release of bacterial enzymes, and sebaceous proinflammatory cytokines.

Active acne management must aim for the reduction of comedonal and inflammatory lesions, psychosocial symptoms and permanent scarring prevention. Various available treatment agents and formulations consider the patient′s age and gender, disease severity, acne duration and tolerability. 

Usage of the topical preparation depends on the extent of the area affected. Creams and gels are preferred for small areas, and lotions for larger surfaces such as the upper torso. Most topical preparations are associated with some side effects like skin irritation, resulting in erythema, desquamation, dryness, stinging and pruritus, especially if applied excessively. This can be, however, improved by initiating the treatment at a low-dose on alternate days, slowly titrating upward as required. 

Benzoyl peroxide (BPO; 2.5% or 5%) possessed comedolytic, anti-inflammatory and bactericidal actions against C. acnes. Thus, can be used alone or in combination with topical antibiotics or retinoids and even during pregnancy. 

Topical retinoids (tretinoin, adapalene) work by reducing micro- and mature comedones, promoting desquamation of follicular epithelium and inhibiting inflammation. Tretinoin may cause photosensitivity; thus, sunscreens must be used along with it. Tolerance of adapalene is better than tretinoin, with lesser skin irritation. Topical retinoids should be continued as maintenance after successful treatment of acne.

Oral antibiotics are great for moderate-to-severe inflammatory acne. They must be used along with nonantibiotic topical agents to reduce antibiotic resistance and increase efficacy. Treatment for at least 4 to 6 weeks is generally required to see a clinical improvement. The dosage is maintained until clearance and then gradually reduced. However, they should not exceed 3 to 4 months.

Doxycycline and erythromycin are the first-line oral antibiotics. While minocycline is the second-line oral antibiotic treatment for acne, it is expensive and associated with more central nervous system side effects, lupus and autoimmune hepatitis. Cotrimoxazole, the third-line treatment, is recommended only when the patient is intolerant or unresponsive to other therapies. It is effective but risks serious adverse events like Stevens-Johnson syndrome/toxic epidermal necrolysis and bone marrow suppression.

The clinicians can use further clinical options such as systemic isotretinoin or oral hormones after assessing the initial therapies for ineffectiveness or recurrence. Isotretinoin is contraindicated in pregnancy, and female patients should be counseled regarding the risk of teratogenicity and appropriate contraceptive methods.

Combined oral contraceptives may be advised for female patients with moderate-to-severe papulopustular acne, signs of hyperandrogenism, need for effective contraception (e.g., during oral isotretinoin use) and as an adjuvant therapy to topical and systemic therapies.

Source: Moosa AS, Quah JHM, How CH. Primary care approach to managing acne. Singapore Med J. 2021;62(11):568-73.