Tretinoin is not widely available over-the-counter in the UK because it is classified as a prescription-only medication. The UK’s regulatory authorities require a doctor or dermatologist to assess a patient’s skin condition before prescribing tretinoin, due to its potency and the potential for side effects such as skin irritation, redness, peeling, or increased sun sensitivity. This ensures that the medication is used safely and effectively, with the correct strength and application routine for each individual. Additionally, strict regulations help prevent misuse or overuse, which could damage the skin or cause adverse reactions. While tretinoin can be legally obtained in the UK, it requires a consultation with a licensed healthcare provider, either in person or through reputable telehealth services, ensuring patients receive professional guidance on proper use.