Pen Needles for NovoLog FlexPen: Which Fit and Best Size to Buy

If you've just been prescribed NovoLog FlexPen, one of the first questions is which needles to buy, because the pen box doesn't include them. The good news is that finding pen needles for NovoLog FlexPen is simple once you know what to look for. This guide covers which needles fit, which lengths and gauges most people choose, how many to keep on hand, and a few FlexPen habits that make every injection go more smoothly.

Which Pen Needles Fit NovoLog FlexPen?

NovoLog FlexPen is a prefilled, disposable insulin pen made by Novo Nordisk. Like most US insulin pens, it uses a standard threaded tip, so it accepts standard screw-on pen needles. Your main options are:

• NovoFine and NovoFine Plus – made by Novo Nordisk and designed for its own pens, including FlexPen. This is the most common pairing.
• BD pen needles (Nano 2nd Gen, Ultra-Fine) – BD states its pen needles are compatible with the major pens sold in the US, including FlexPen.
• Other universal screw-on needles – most brands that list "universal" or "fits all major pens" will thread on. Check the box for a compatibility statement before you buy.

Pen needles are not specific to insulin type, so the same box works whether you use FlexPen, a Tresiba FlexTouch, or another threaded pen.

Best Pen Needle Size for NovoLog FlexPen

Needle choice comes down to length (mm) and gauge (G, where a higher number means a thinner needle).

• 4mm, 32G – the shortest, thinnest common option. Current injection-technique guidance recognizes 4mm needles as suitable for most adults regardless of body size, and many people find them the most comfortable. NovoFine Plus 32G 4mm and BD Nano 2nd Gen 32G 4mm are both in this category.
• 5–6mm – a middle ground some people prefer, often because it's what they started on.
• 8mm – longer needles are still available, but they're less commonly recommended today because they raise the chance of injecting into muscle, especially for leaner people.

For a deeper look at the trade-offs, see our guide to 4mm vs 6mm vs 8mm pen needles. If your healthcare provider has recommended a specific length, stick with that.

How Many Needles Will You Need?

Use a new needle for every injection. NovoLog is a mealtime (rapid-acting) insulin, so many people inject it several times a day. Someone injecting three times daily uses about 90 needles a month, which is why a 100-count box is the standard size. If you also use a basal insulin pen, count those injections too.

Not sure which needle you'll like? A small NovoFine Plus 4-count trial pack lets you test the feel before committing to a full box, and it doubles as a spare supply for your bag or car.

FlexPen Tips That Make Needles Work Better

• Screw the needle on straight. Remove the paper tab, then twist the needle on until it's snug. Cross-threading can cause leaks or a bent needle.
• Do the safety test (air shot) before each injection. The FlexPen instructions call for dialing 2 units, tapping out air bubbles, and pressing until a drop appears at the needle tip.
• Hold the needle in the skin. After the dose counter returns to 0, keep the needle in place for at least 6 seconds, as the FlexPen instructions direct, so the full dose is delivered.
• Remove the needle after every injection. Storing the pen with a needle attached can let air in and insulin leak out.
• Dispose of used needles in an FDA-cleared sharps container or a heavy-duty plastic household container, following your local rules.

Quick Buying Checklist

• Screw-on (threaded) pen needle labeled compatible with Novo Nordisk pens
• Length your provider recommended (4mm fits most adults)
• Gauge you find comfortable (31G–32G is typical)
• Enough for one needle per injection, plus a small spare supply
• Sealed, unexpired boxes from a reputable seller

FAQ

Do I need a prescription for pen needles?
In most of the US you can buy pen needles without one, but insurance plans usually require a prescription to cover them. Check with your plan if you want to use insurance.

Can I use BD needles on a NovoLog FlexPen?
Yes. BD pen needles are designed to fit standard threaded pens, including FlexPen.

Does the needle affect my dose?
No. The pen controls the dose; the needle only delivers it. Always follow your healthcare provider's instructions for dosing and injection technique.

Browse all compatible options in our pen needles collection. Use code WELCOME10 at checkout for 10% off your order.

This article is for general information only and isn't medical advice. Talk with your healthcare provider about the needle length, technique, and insulin plan that's right for you.