What Are PDE5 Inhibitors and How Do They Work?

Erectile dysfunction (ED) is insanely common, and if you’ve ever Googled it at 2 a.m., you’ve definitely seen names like Sildenafil or Tadalafil. These sit in a group of meds called PDE5 inhibitors — which sounds very science-y until you break it down, and that's what we'll be doing today. So what actually is PDE5, and how do these meds help you get (and keep) a proper erection?

 

What is PDE5?

 

PDE5 stands for phosphodiesterase type 5 — it’s an enzyme living in the walls of blood vessels, including the ones in your penis. Its main job is to break down a chemical messenger called cGMP (cyclic guanosine monophosphate), which controls how relaxed or tight those blood vessels are. When cGMP is high, blood vessels relax and open up; when PDE5 breaks it down, they tighten again and blood flow drops.

 

 

• cGMP = relaxes blood vessels → more blood flow into the penis

• PDE5 = breaks down cGMP → reduces that blood flow

 

Both are normal and necessary for controlling blood flow to different parts of the body. The issue starts when PDE5 clears out cGMP too fast, making it harder for you to get or maintain an erection long enough for sex.

 

How erections actually work

 

From the outside, an erection looks simple right? But inside your body, it’s your brain, nerves, hormones, and blood vessels all working together like a team.

 

• Sexual arousal starts in your brain, which sends signals down your spinal cord to nerves in the penis.

• These nerves release nitric oxide (NO) — the “go” signal that kicks off the erection process.

• Nitric oxide triggers the production of cGMP in the smooth muscle of the penis.

• cGMP relaxes the muscle in the blood vessel walls, so the arteries widen and blood rushes into the erectile tissue.

• The penis fills with blood, hardens, and veins that drain blood out are partially compressed, helping you stay hard while you’re turned on.

• When the arousal fades, PDE5 breaks down cGMP, the muscles tighten again, and the erection naturally fades.

 

So PDE5 isn’t “bad” — it’s part of the shutdown system that stops erections from lasting forever. But if it steps in too early or too aggressively, you can lose firmness or lose the erection sooner than you want.

 

What PDE5 inhibitors actually do

 

PDE5 inhibitors like Sildenafil, Tadalafil, and Vardenafil are designed to block the PDE5 enzyme from breaking down cGMP too quickly. That means:

 

• cGMP sticks around for longer

• Blood vessels in the penis stay relaxed for longer

• More blood can enter and stay in the penis during sexual arousal

 

It becomes way easier to get and keep a firm erection when you’re turned on, not randomly in the middle of the day. Think of it like extending the time window where your body can successfully turn arousal into a proper erection — you’re not forcing an erection by any means; you’re giving your system more time and support to basically do what it’s already trying to do.

 

Different PDE5 inhibitors mainly differ in:

 

• How fast they start working (onset)

• How long they last in your system (duration)

 

For example, Sildenafil usually lasts for a few hours, while Tadalafil can stay active for up to 36 hours, giving more flexibility around timing sex.

 

What PDE5 inhibitors don’t do

 

There are a few myths that need to be killed off:

 

• They don’t boost sex drive
  These medicines work on blood flow, not on desire or libido. You can still not be in the mood and nothing will happen.

• They don’t cause automatic erections
  You still need some form of sexual stimulation — physical, mental, or both — for the erection process to kick in. No arousal = no erection, even with the tablet.

• They don’t permanently “fix” ED
  You generally need to take them each time (or on a schedule, depending on the drug) when you’re planning to have sex. Stopping the medicine usually means going back to your baseline.

Are PDE5 inhibitors safe?

 

When prescribed correctly, PDE5 inhibitors are well-studied, clinically approved medicines that have been used by millions of men worldwide over many years. They’re considered first-line treatment for erectile dysfunction in most clinical guidelines.

 

Side effects can happen — often things like:

 

• Headache

• Flushing

• Blocked or runny nose

• Indigestion

• Mild dizziness or visual changes

 

These are usually mild and wear off as the drug leaves your system. That’s why getting them through a proper consultation matters. A pharmacist can:

• Check your heart and blood pressure history

• Make sure they’re safe to use with any meds you’re already taking (for example, they must not be mixed with nitrates for chest pain)

• Help you pick between options like fast-acting Sildenafil or longer-lasting Tadalafil

• Adjust your dose if you get side effects or not enough effect

Why understanding PDE5 actually helps

 

Knowing what PDE5 and PDE5 inhibitors do takes some of the pressure off your shoulders. ED often isn’t about “being less of a man”; it’s usually about blood flow, chemistry, and sometimes underlying health issues like heart disease, diabetes, or stress. These medicines don’t replace you — they support your body’s natural erection system so you can actually enjoy sex again and feel more confident with your partner.

 

If you’re thinking about trying a PDE5 inhibitor, using a legit UK-registered pharmacy like Cured Pharmacy and going through a short online consultation is usually the easiest, least awkward first move.