Policies to improve access to medicines for children in Nigeria do not include compounding as a source of medicines. Compounding is often applied as a last resort in health institutions to provide age-appropriate formulations usually for oral use in young children; but it bears some risk. Some countries have adopted policies aimed at reducing the risk based on available data. There is not much data for Nigeria. This retrospective study examined compounding records from January to December 2011 in a sample of seven hospitals to describe what medicines for oral use were commonly compounded in Nigeria. It then determined if these medicines were commercially available in forms suitable for use in children in selected countries—the United Kingdom, United States and India. The study found that out of 2845 items compounded, over 65% were medicines for cardiovascular conditions, diarrhoea or tuberculosis. The main reason (96%, n = 2399) for compounding was the unavailability of age-appropriate formulations. Medicines were almost all compounded using simple syrup, vitamin C or vitamin B syrups as suspending vehicles. Final products were all oral liquids. Comprehensive stability testing was not reported for the products. Almost all of the commonly compounded medicines were found to be commercially available in dosage forms suitable for use in children in the selected countries. These medicines were all listed in the World Health Organization Essential Medicines List for children as well as in the current edition of the Essential Medicines List of Nigeria. The fact that they were compounded highlights the need for improved access to age-appropriate dosage forms for children in Nigeria. The study recommends policy expansion through a three-pronged approach to improving access: increased supply through facilitated importation/accelerated product registration, or in-country manufacturing; rational drug use including therapeutic substitution, and establishment of a national formulary for compounding.