Hydra Pen H6 Replacement Cartridges

The four heads, and where each one lands

Depth is set on the pen — the H6 dial turns from 0.25 mm up to 2.0 mm — so what a head decides is the density of the micro-channels created in one pass, and how the serum is laid down along it. The Nano-R is the exception: with no needles in it, depth does not apply to it at all.

Safe depth by concern is in our needle depth guide — at home, keep facial depth at or below 1.0 mm even though the pen will go to 2.0 mm; the deeper end of the range is for trained practitioners. Still deciding between two densities? Our cartridge guide walks the same choice through in more detail.

The reservoir arrives empty — that is the point

A sealed head has to sit on a shelf until you use it, and a head that shipped with liquid already inside it could not. So the 3 mL chamber comes dry and you fill it, which also means the choice of what goes into your skin stays with you rather than with whoever packed the box.

The pen then pushes that liquid through as the head moves, which is the difference between an H6 and a needling-only pen: you are not stopping every section to reapply by hand, and the serum is not drying on the surface while you work elsewhere. The same feature is why the head does not need a second product on the skin to glide.

What goes in — and what stays out

• Use a sterile product made for micro-needling. A session opens channels in the skin, so what you load matters: choose a serum or ampoule formulated for this use rather than an everyday cosmetic one.
• Avoid jarred skincare, however good it is. Jarred products are not sterile to begin with and pick up more each time they are opened, and they carry preservatives and fragrance that have no business in a fresh channel.
• Never let a dropper touch your skin, then go back into the bottle — that is how a clean product stops being one.
• Fill it full before you start. It is far easier to load a head at the beginning of a session than to top one up with serum on your hands.

Filling it, and keeping it flowing

• Clear the air first. After filling, hold the head upright and tap the serum side the way you would tap a syringe — a trapped bubble is the usual reason a head looks full but delivers nothing.
• Work at 90°. The feed is built to run with the head square to the skin, so tilting it is what produces the dripping and the uneven coverage.
• Start on the lowest flow setting and come up. Rising through the settings is also how you find where a given product runs best for you.
• Expect a change in sound as it empties. The pen starts to make a wet, sucking note as the chamber runs low — treat that as the cue to top up rather than running dry.
• Refilling mid-session is normal. The chamber can be refilled during a session, so a top-up is routine rather than a sign that something is wrong.

How far a 3 mL reservoir goes

For a full-face pass, 3 mL is normally the whole session's worth. Because the head lays the serum down as it travels rather than you reapplying by hand, very little of it is lost to the air or to your fingers, and that is what makes a chamber this size go as far as it does.

How far it actually stretches is not fixed, though — it depends on the flow setting you choose and on how much you work beyond the face. 

What a sealed H6 pack looks like

• One sterile blister per head, with manufacturing and expiry dates printed on it.
• Single use. A head is spent when the session ends — a reused one drags rather than cutting clean channels, see can you reuse Dr. Pen cartridges?
• A listing you can verify. We are an authorised Dr. Pen retailer and stock arrives through the official supply chain — how to verify your Dr. Pen.
• Packs of 5, 10 and 20. If you treat on a regular schedule, the larger pack is the one that brings the cost per head down.

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