Non-Itchy Rash Under the Breasts in Pregnancy
The most likely diagnosis is intertrigo, a friction-related inflammatory dermatosis that commonly affects the inframammary folds during pregnancy and should be treated with topical nystatin and moisture control measures. 1
Why Intertrigo is the Most Likely Diagnosis
The bilateral location under the breasts combined with absence of itching strongly suggests intertrigo rather than pregnancy-specific dermatoses, which typically present with pruritus and different distribution patterns 1
Polymorphic eruption of pregnancy (PEP) presents with pruritic urticarial papules and plaques on the abdomen and proximal thighs, typically in the third trimester—not under the breasts and not without itching 2, 1
Atopic eruption of pregnancy (AEP) affects the face, eyelids, neck, antecubital and popliteal fossae, trunk, and extremities with an eczematous, pruritic rash—again, not matching this presentation 2, 1
Intrahepatic cholestasis of pregnancy presents with pruritus WITHOUT any primary rash, predominantly affecting palms and soles, worse at night 2, 1
Pemphigoid gestationis is rare and associated with vesicles and bullae, not a simple rash under the breasts 2, 1
First-Line Treatment Approach
Immediate Non-Pharmacologic Measures
Maintain skin dryness in the inframammary folds by ensuring thorough drying after bathing and throughout the day 1
Apply emollients regularly, especially after bathing, as this forms the basis of therapy for inflammatory skin conditions during pregnancy 1
Recommend loose, breathable clothing made from natural fabrics to reduce friction and irritation in the affected areas 1
Consider barrier creams or moisture-wicking fabric inserts to reduce maceration in the skin folds 1
Pharmacologic Treatment
Topical nystatin is the preferred antifungal agent for intertrigo in pregnancy, particularly in the first trimester 1
Use nystatin suspension 100,000 units/ml or pastilles 200,000 units applied locally to affected areas 1
If moderate inflammation is present, moderate-potency topical corticosteroids are safe and appropriate—avoid very potent formulations 1
Critical Safety Warnings
NEVER prescribe systemic azole antifungals (fluconazole, itraconazole) in the first trimester due to teratogenic potential—use topical nystatin instead 1
Even topical azole preparations should be used with caution in the first trimester 1
Do not use very potent topical corticosteroids for initial management—moderate potency is sufficient and safer 1
When to Reconsider the Diagnosis
If the rash does NOT respond to intertrigo treatment within 1-2 weeks, reconsider pregnancy-specific dermatoses 1
If the patient develops pruritus without a primary rash, immediately check serum bile acids to rule out intrahepatic cholestasis of pregnancy, which carries significant fetal risks including stillbirth 2, 1, 3
If vesicles or bullae develop, consider pemphigoid gestationis and refer for direct immunofluorescence studies 1
Address Predisposing Factors
Screen for diabetes mellitus, which increases the risk of candidal intertrigo 1
Ensure proper hygiene with gentle cleansing and thorough drying of inframammary folds 1
Provide weight management counseling as appropriate 1
Common Pitfalls to Avoid
Do not assume all pregnancy rashes are benign—if severe pruritus develops or systemic symptoms appear, evaluate for intrahepatic cholestasis of pregnancy which carries fetal risks 1, 3
Do not delay bile acid testing in any pregnant patient who develops pruritus, even if a rash is present, as excoriations from scratching can mimic a primary rash 3
Do not neglect to address predisposing factors such as diabetes screening, as this affects treatment success 1