AITAH for accidentally letting my sister in law get chemical burns on her face.

My husband (26M) and I (26F) bought our first home 7 months ago. His younger sister (16F), who just got her license, frequently shows up unannounced and has trouble taking ‘no’ for an answer.

Last Friday, she came over after dinner and asked to stay the night. We agreed since we had no plans. She asked to shower, so we let her use ours, as our guest bathroom isn’t stocked yet. I splurge on salon-quality haircare products because my hair is unruly, and my $27 shampoo bottle was brand new. Later, I found half the shampoo and nearly all the conditioner gone, along with my skincare scattered across the counter. She’d used almost $50 worth of hair products, and all of my skin stuff including my prescription skincare stored in a pharmacy bag.

I asked her to bring her own products next time, as I wasn’t comfortable with how much she used. I was in no way rude I just explained the I splurge on really expensive products and can’t afford to have 50+ dollars of product gone everytime she showers here. She called me selfish in a passive aggressive way and ended up leaving.

By Tuesday, her skin was red, peeling, and breaking out terribly. At dinner with my in-laws Tuesday, she blamed me for not warning her about my skincare. I explained I hadn’t expected her to dig through my drawers and use prescription products, which are expensive and took my skin weeks to adjust to. My Father in Law said I should pay for a doctor visit, but my husband refused, arguing that at 16, she should know better and that it was inappropriate for her to look through my medicine bag to even find the prescription product that was likely the culprit for the irritation.

Am I at fault for not warning her? I wouldn’t go through someone’s personal products, let alone use their stuff like it was my own. I would’ve been happy to share some skin products, not my prescription cream. She also brought up that I got mad she used so much shampoo and conditioner and basically made me look really bad in front of my in laws. Admittedly I was upset about the shampoo and conditioner and the fact that she left a huge mess on the counter, but I was very calm and just explained money is tight as we just bought our house and I didn’t want her to use months of products in one shower. Anyways let me know what you all think?