Normally take lisinopril but don't have any. Can I take a H145 white oval pill?

They are similar (do not know the similarity of doses of each) and both are prescription medications only, meaning I am not qualified to make a decision for you , I am not a medical professional. You know pill imprint H145 is Losartan Potassium according to the pill identifier of Drugs.com, however Lisinopril belongs to the drug class of Angiotensin Converting Enzyme Inhibitors and Losartan to the drug class of Angiotensin receptor blockers.

https://www.drugs.com/drug-class/angiotensin-converting-enzyme-inhibitors.html

https://www.drugs.com/drug-class/angiotensin-ii-inhibitors.html

Click on the link to read a comparison between the two medications:

https://www.drugs.com/compare/lisinopril-vs-losartan

Source: Drugs.com

You must find a source that can provide you with Lisinopril, perhaps try a hospital, etc,,, but do not self medicate, the doses of each may not be the same and this makes it risky and not safe for you.