In this case, the safest option for relieving back pain during pregnancy would be to use Tylenol (acetaminophen). It is a medication that has been extensively studied and is considered safe to use throughout pregnancy. If you prefer a topical medication, you can use a 10% triethanolamine salicylate cream for short-term use on a small area of your back. However, it is recommended to prioritize Tylenol for pain relief during pregnancy. Seeing a chiropractor for treatment is also a good choice for managing back pain.