Retinol

No. Both are retinoids, which are vitamin A derivatives, but tretinoin is retinoic acid itself and requires a prescription in the US. Retinol has to be converted by your skin into retinoic acid first, so it's gentler and slower. Same family, different strength and speed.

Plan on months, not days. Some people see smoother texture after a few weeks, but changes in fine lines and dark spots usually take about three months or more of steady use. Results vary by product and skin. Irritation, if you get it, tends to show up before any benefits do.

You can, but night is the standard advice. Retinoids can make skin more sensitive to sun, and retinol is easily degraded by light. If you use it in the morning, finish with broad-spectrum SPF 30 or higher. You need daily sunscreen either way, especially if you're using retinol.

Most doctors advise skipping it. Oral vitamin A-derived drugs are known to cause birth defects, and the evidence on topical retinol is limited, so the cautious default is to avoid it while pregnant or trying to conceive. Ask your OB or dermatologist what to use instead.

Sometimes. Retinoids speed up skin cell turnover, so people prone to clogged pores may get a temporary breakout in the first weeks. Irritation can also look like pimples. If the breakouts drag on for months, or your skin burns and peels, cut back and talk to a dermatologist.