According to the sources provided, infants can take liquid Advil, but only under certain conditions. Liquid Advil is a brand name for ibuprofen, a nonsteroidal anti-inflammatory drug (NSAID) used to relieve pain and reduce fever. The drug is available over-the-counter (OTC) and by prescription.

The first source [1] indicates that Advil is the brand name for ibuprofen, and the drug is available in different forms, including tablets, capsules, and liquid suspension. The second source [2] explains that ibuprofen is safe and effective for infants over six months of age, but parents should consult a healthcare provider before giving it to their child. The third source [3] confirms that Children's Advil Suspension is safe for children as young as six months old, and parents should follow the dosing instructions on the label or as directed by a healthcare provider.

However, it is important to note that infants under six months of age should not take ibuprofen, as it may cause serious side effects, including stomach bleeding and kidney damage. Additionally, parents should always follow the dosing instructions carefully and avoid giving their child more than the recommended amount.

In conclusion, infants can take liquid Advil (ibuprofen) under certain conditions, but parents should consult a healthcare provider before giving it to their child, follow the dosing instructions carefully, and avoid giving it to infants under six months of age.

Sources:
[1] https://www.drugpatentwatch.com/p/tradename/ADVIL
[2] https://www.healthychildren.org/English/safety-prevention/at-home/medication-safety/Pages/Ibuprofen-for-Fever-and-Pain.aspx
[3] https://www.advil.com/faqs-en/childrens-advil