In today’s supplement-obsessed culture, it’s easy to assume that if something is sold over the counter and marketed as “healthy,” it must be safe and beneficial for everyone. Multivitamins, powders, and capsules have become part of many daily routines, often taken without a second thought about dosage, interactions, or whether the body actually needs them. But more isn’t always better, and certain supplements can do more harm than good when taken unnecessarily or in excess. Just like skincare, supplementation should be targeted and intentional, not driven by trends or health claims that lack real scientific backing.
To better understand some of these popular supplements, we spoke with Dr. Ali Cadili, is completing a fellowship in Surgical Critical Care at the University of Connecticut. Dr. Cadili explains that some popular supplements may undermine skin health by damaging collagen, reducing elasticity, and accelerating visible signs of aging. Here are two commonly used supplements he says can negatively affect your skin’s firmness and contribute to premature aging,
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1. Iron Supplements
Iron is an essential mineral, but it’s also one of the clearest examples of a supplement that should only be taken when there is a true, confirmed need. Many people assume iron will boost energy or improve overall health, but taking it without a diagnosed deficiency can overwhelm the body. Excess iron isn’t easily excreted, so it can accumulate in organs and create oxidative stress that affects everything from the gut to the skin. Over time, this buildup can interfere with collagen integrity and contribute to dullness, inflammation, and accelerated aging rather than preventing it.
As Dr. Ali Cadili explains, “Iron supplements are extremely valuable in anemic patients (whether due to chronic bleeding or from other causes) as iron plays a critical role in oxygen transport and delivery to the body's tissues. It is extremely valuable in the context of a confirmed deficiency with dosage and duration of the supplementation guided by a medical professional.” He cautions that “Inappropriate excessive supplementation, on the other hand, can lead to iron toxicity (also called iron poisoning or iron overload) which can result in short term symptoms such as abdominal pain, nausea and vomiting, as well as diarrhea.” Dr. Cadili adds that long-term overuse can have severe consequences, including “liver or kidney failure, seizures, coma, low blood pressure, shock, and increased risk of infection.”
2. Vitamin A Supplements
Vitamin A is often praised for its skin benefits, which makes it especially tempting to supplement, but it’s another nutrient where more is definitely not better. While adequate vitamin A supports cell turnover and skin repair, excessive intake can disrupt the skin barrier, increase dryness, and paradoxically speed up visible aging. Because vitamin A is fat-soluble, it stays in the body longer, increasing the risk of toxicity if taken in high doses or combined unknowingly with fortified foods and skincare treatments.
According to Dr. Cadili, “Vitamin A supplements in appropriate doses can support skin elasticity and repair and collagen production which helps prevent/reduce skin wrinkles and improve overall skin quality in deficient individuals. This should be taken under medical direction and guidance to avoid the serious complications of overuse or misuse.” One of the most concerning effects, he notes, is that “One of the most feared adverse events of overuse is Vitamin A toxicity which leads to hair loss, and poor skin quality (rough dry peeling skin) i.e. disruption in the skin's barrier protection function and accelerated skin aging.” More serious consequences include blurred vision, headache, muscle weakness, drowsiness and irritability.”
