IF YOU GO to a convenience store and see a product behind the counter with a name like “Boner Blaster 5,000,” it’s a surefire way to know a supplement is not legit. But not all scams are that obvious. That’s because supplements made of “herbal Viagra” or other natural ingredients don’t always work.

“Even if you buy them at a big retailer, and they seem to be made of ‘natural’ ingredients, be cautious,” says Jamin Brahmbhatt, MD, urologist at Orlando Health. “No one is regulating this stuff.”

That’s concerning. When it comes to supplements, it’s not clear what you could be putting in your body. There’s always the chance it could harm your overall health — and make any erectile dysfunction problem worse. Experts narrowed it down to five options worth considering.

The Best Supplements for Sex

Nathan Starke, MD, urologist at Houston Methodist, says his patients ask him about supplements “all the time.” While supplements are usually safe for most people, he urges caution when choosing one. If you’re looking for an extra boost, consider the following expert-backed options:

L-Arginine

L-arginine is an essential amino acid that may benefit both heart health and erectile function, says Dr. Brahmbhatt.

One study in the journal Andrology found that patients with severe or complete erectile dysfunction had L-arginine levels that were significantly lower than those of men with milder forms of ED. In guys with mild-to-moderate ED, three months of L-arginine supplementation significantly increased the speed of blood flow to the penis and improved erectile function. One caveat was that L-arginine supplements alone were not as effective in guys with severe ED. However, L-arginine effects may work better when paired with ED medications. An 8-week trial had men ages 50 and older take L-arginine supplements with sildenafil (Viagra) or sildenafil every other day. Those results showed greater erectile function in guys taking the combo treatment than sildenafil alone.

L-arginine is broken down by the body into nitric oxide, a smooth muscle relaxer that allows for more blood flow to the penis, which is important for erections. (Drugs including Cialis and Viagra block the breakdown of nitric oxide in the body, so there are higher circulating levels to help with erections.)

L-arginine is found in most protein-rich foods such as red meat, poultry, beans, and dairy products. The Mayo Clinic marks L-arginine as generally safe but cautions people who take blood pressure medications to talk to a doctor first.

This is good advice for any supplements if you’re on blood pressure medications, Dr. Brahmbhatt says. That’s because a product like L-arginine can reduce your blood pressure — which is great if it’s a bit too high, but not if you’re already bringing it down with meds. In that case, you may see a sudden and dramatic drop in pressure that could cause you to faint, or in extreme cases, have a stroke.

If you’re not on those meds and want to try the amino acid, Dr. Brahmbhatt suggests starting at a dose of about six grams a day to see how you tolerate it. In some people, the supplement can cause side effects, including nausea, abdominal pain, diarrhea, and bloating.

L-Citrulline

In addition to L-arginine, L-citrulline is often recommended to help produce stronger erections. This is because L-citrulline is converted in the body to L-arginine, explains Peter Tsambarlis, MD, urologist at Northwestern Medicine. One review found that taking L-citrulline increased blood levels of L-arginine more effectively than L-arginine supplements did, likely due to higher production of nitric oxide (NO).

“Nitric oxide is involved in vasodilation (widening and opening up of blood vessels), which can begin and maintain the erectile response,” says Michael Eisenberg, MD, urologist at Stanford Medicine. Nitric oxide is considered the main neurotransmitter responsible for causing an erection by relaxing penile smooth muscle.

Omega-3s

Omega-3 fatty acids are a lukewarm maybe when it comes to protecting your heart and your erections. The research goes back and forth about whether fish oil supplements are really helpful for the heart. If the scales tip toward them being helpful to your heart, then your erections may benefit as well, says Dr. Brahmbhatt. That’s because heart-healthy changes are geared toward improving blood flow and increasing the size of blood vessels.

Your penis has some of the smallest blood vessels in your body, meaning they are more prone to getting clogged up. Impeded blood flow is bad for erections, so anything that improves blood flow is good.

That’s why many blood pressure medications list erectile dysfunction as a side effect — the very medications meant to protect your cardiovascular system can sometimes interfere with the blood flow needed for an erection. Omega-3s, by contrast, support vascular health without that trade-off, which is why doctors consider them a reasonable option for men looking to support both heart health and sexual function.

As with any supplement, it’s worth discussing omega-3s with a healthcare provider before adding them to your routine, particularly if you’re already taking medications that affect blood pressure or clotting.