As an expert in skincare ingredients, I can provide you with information on retinol. Retinol is a form of vitamin A that is widely used in skincare products for its potential anti-aging benefits. Over-the-counter (OTC) retinol products typically have a lower concentration of retinol compared to prescription-strength options.

The strongest retinol available over the counter usually contains up to 2% retinol. However, it's important to note that the strength of retinol is not the only factor to consider. Factors such as formulation, stability, and the presence of other beneficial ingredients can also impact the overall effectiveness of a retinol product.

It's crucial to start with a lower concentration of retinol and gradually increase it to allow your skin to adjust and minimize the risk of irritation. Additionally, using a broad-spectrum sunscreen during the day is essential when incorporating retinol into your skincare routine, as retinol can increase sun sensitivity.

If you are looking for a stronger retinol treatment, it is advisable to consult with a dermatologist who can prescribe a higher-strength retinoid product that suits your skin's needs. They can provide personalized recommendations based on your skin type, concerns, and medical history.