24, male, does SD gives instant shedding or there is a period of delay corresponding to the telogen phase? (Photo)

It’s definitely frustrating to be dealing with both seborrheic dermatitis (SD) and androgenetic alopecia (AGA), especially after having a serious illness like pneumonia. To answer your question, SD doesn’t usually cause instant shedding. Instead, there’s typically a delay that aligns with the hair’s telogen phase, which is about 2-3 months. That’s why you’re noticing shedding now—it’s likely the combined effects of the SD flare-up and the stress from your illness back in January.
Poorly managed seborrheic dermatitis can contribute to inflammation in the scalp, but it doesn’t directly cause miniaturization like AGA does. However, chronic inflammation could weaken hair follicles and lead to more shedding or make thinning more noticeable. While the inflammation from SD can worsen shedding, the miniaturization process is driven by DHT and your genetics.
As for the hair falling out with sebum attached, that sounds like it could be from the SD. The greasy buildup you’re seeing isn’t a typical dandruff flake but rather excess oil and dead skin cells that build up due to the SD. Managing the SD can help reduce this buildup and might ease some of the shedding.
I’d recommend continuing with your AGA treatments (like finasteride or minoxidil) and managing the SD to help control the inflammation and improve scalp health.