As a rule, over-the-counter treatments (which are the most of what you'll find available) are placebos, or have untested/unproved results. There are some interesting things you can use to make sex fun/interesting (I've heard weirdly positive things about using 'Miracle Fruit' before engaging in oral sex), but in general, most aren't all that helpful.
Products with proven results (like Viagra, for example) are available, but they tend to be provided with prescription, and mostly for sake of people with medically-related performance problems.
Honestly, your best bet to improve your libido is improve your health and fitness. A healthy, balanced diet, and lots of exercise translate into improved circulation, greater endurance, and better overall stamina.
This is what I use. It's amazing in my opinion. I would definitely get more than one though. Just so you have a back up.
Tastelife Waterproof Mattress Pad Protector Cover (Fitted 8" - 21" Deep Pocket) (Queen, White) https://www.amazon.com/dp/B0722WRYVB/ref=cm_sw_r_cp_apa_jmn1zbHAD23FT
In my opinion, this is the best tool you can buy for grooming all over the body.
Philips Norelco BG2040/34 Bodygroom 7100 (Packaging May Vary) https://www.amazon.com/dp/B0037HP9OA/ref=cm_sw_r_other_awd_LZhNwbSRRB8Q4