Our most popular product, this fast-acting, results-orientated formula offers a multitude of benefits with long term results. This potent botanical serum generates a cool tingling sensation on application as it penetrates and works brilliantly by itself or as part of our specific regimes. Dermstore has partnered with Flex to allow you to use your Health Savings Account (HSA) or Flexible Spending Account (FSA). This means you can now use your HSA or FSA debit card to buy iS Clinical products with pre-tax dollars, resulting in net savings of 30-40%, depending on your tax bracket. Eligible for HSA/FSA with a letter of medical necessity at checkout. From dermatologist-recommended treatments to solutions for chronic skin conditions like acne, eczema, and rosacea, these products are both effective and eligible. | iS Clinical Active Serum, 0. 5 oz | Dermstore