What Is A Filter Needle

If you’re one of the many people worried about broken glass particles in your glass ampoule when you break it open, then today’s article is for you.

One of the biggest causes for concern in the medical and TRT community is broken glass particles when opening glass ampoules. Especially when drawing up your medication for an injection (for example, with hormone replacement therapy).

I get questions about this all the time (as you can see below) and this is naturally a valid cause for concern.

Question: “What if really small pieces of glass end up inside the ampule? Will the needle draw it up?”

As someone who uses glass ampoules myself, I never really used to worry about this. However, after receiving numerous questions on this topic, and doing more investigation, I can certainly understand the need for clarification and risk management when it comes to opening glass ampoules.

In this article, we’ll take a look at the risks associated with using glass ampoules and what you can do to prevent contamination during your own injections.

Please note: I am not a doctor, so please consult your doctor or medical provider before taking any medical action regarding your health.

Risk Of Harm From Glass Particle Contamination

As is normal in the medical community, the information available on this topic is mixed.

While the general consensus indicates a definite risk of glass particle contamination when using glass ampoules, the degree of this risk is not clearly specified. Also, there it is unclear whether glass particle contamination poses any significant risk of harm.

The closest I could find to anything measurable, was the risk of glass contaminants when using large bore needles like an 18G and a 21G needle. This showed a risk of at least one glass particle being found in 22-56% of regular large bore needles. There were 0 glass particles found when a filter needle was used.

One study indicated that the risk of harm from glass particle contamination was possible:

“Exogenous contaminations by glass and metals can reach several sites in the organism. They trigger organic reactions that may give rise to injuries.”

Another study concluded that there was a lack of evidence to conclude significant harm from glass particle contamination:

“In conclusion, studies have shown evidence of glass particle contamination in injectable drugs drawn from glass ampoules, and have generally demonstrated that use of filter needles would reduce patient exposure to these particulates. There is, however, a lack of definitive evidence for significant harm from the injection of these glass particle contaminants. Arguments that practice should err on the side of caution until studies can prove that contamination does not cause harm are valid, however it is unlikely these studies will be able to be conducted. Considering the limited evidence for harm of glass particulate injection found in well over fifty years of observation, it would appear that the cost of filter needles outweighs the questionable benefits gained from their universal introduction for aspiration of intravenously administered drugs from glass ampoules.”

This last study’s findings seem to align with what we see anecdotally in the community. However, precautions should still be taken.

Factors Affecting Glass Particle Contamination Risk

According to the studies (references listed at the bottom of this article), there is a significant risk of glass particle contamination, which can be affected by multiple factors, including:

  • The size of the glass ampoule
  • The technique used to open the glass ampoule
  • The size of the needle used
  • Whether a regular needle or a filter needle was used

Precautions To Reduce Risk Of Glass Particle Contamination

At this stage it is unlikely that glass particle contamination poses any harm to you.

However, there are certain precautions you can take to reduce the likelihood of glass particle contamination.

Filter Needles

Filter Needle vs Regular Needle

A Filter needle (top) vs a regular needle.

Filter needles are needles with small, glass filtering devices at the base of the needle.

Filter needles have been shown to eliminate or significantly reduce the risk of glass particle contamination.

If you are highly concerned about glass particle contamination, then filter needles are the most reliable precaution you can take.

Just be aware that filter needles are significantly more expensive than regular needles, coming in at up to double the price. However, given that needles are so cheap (especially in bulk),they aren’t actually that expensive.

Naturally, the more frequently you do injections, the greater the risk of glass particle contamination. So if you inject 2 or more times a week, doctors suggest using a filter needle.

Correct Ampoule Opening Technique

A common cause of glass particle contamination is when people (including medical professionals) don’t know how to open glass ampoules correctly.

Incorrect technique greatly increases the risk of contamination, as more glass may break and enter the ampoule.

If you are unsure on how to open a glass ampoule, please check out the video I did demonstrating the correct technique:
YouTube: How To Open A Glass Ampoule The Right Way

Using Ampoules With Facilitator Systems

In order to decrease the risk of contamination when opening glass ampoules, facilitator systems were developed to help break open these ampoules.

The two main ones are the VIBRAC system (as seen by the line/ring across the neck of the ampoule) and the OPC (one point cut) system, as seen by the round dot above the neck of the ampoule).

85% of ampoules use these systems, so it’s likely that your medication already comes in one of these. For example, the Sustanon that I use for my testosterone replacement therapy uses the OPC dot system.

If your ampoules do not utilise such a system, discuss this with your doctor.

Use Smaller Bore Needles

If you don’t wish to fork out the extra cash for filter needles, you can try using smaller bore needles for drawing your medication from the ampoule. For example, a 23G needle.

In theory, this should decrease the risk of particles getting in, or at least prevent the larger glass particles from entering the syringe. However, this has not been tested and you do so at your own risk.

This method may still let smaller particles by and enter the syringe, so it’s by no means a reliable method and should only be considered as a last resort.

Using smaller bore needles will also make drawing the medication a little more difficult, as the needle is smaller and the solution will take longer to draw up.

Use Single/Multi-Dose Vials Instead of Ampoules

Example of a multi-dose vial

Finally, the other way to avoid glass particle contamination is to use single or multi-dose vials if possible.

Multi-dose vials come in larger volumes, for example 10ml, and have a rubber seal through which you insert the needle and draw the solution into the syringe. There is no glass to break and this is a much easier form of drawing your medication.

Typically, if you’re being prescribed your medication in a glass ampoule, it’s due to the fact that they probably don’t have or aren’t allowed to prescribe single/multi-dose vials. However, I just wanted to list this for those that weren’t aware of it.

Speak to your doctor and ask them about multi-dose vials if you haven’t already.


While there seems to be a somewhat significant risk of glass particle contamination when opening ampoules, certain safety precautions can be taken to reduce this risk.

The likelihood that there would be any significant harm from glass particle contamination however, is still debatable.

Despite this low risk of harm, studies indicate that it’s still better to err on the side of caution and use filter needles, especially for frequently administered injections.

If you find the cost of filter needles too expensive, then using a combination of the other safety precautions as an alternative may decrease the risk of glass contamination.

I would also like to stress that you should not let information like this deter you from your medication. While it might sound alarming, in reality, the risk of any significant harm to you is very low. I have yet to hear of anyone in the TRT community who has had complications because of glass particles.

If this is major cause of concern for you, then speak to your doctor and discuss alternatives to glass ampoules, if they are open to it.

If you have any experiences with glass ampoules and glass particle contamination, or using filter needles, please share your experience or questions in the comments sections below.

Until next time.


Glass micro-particulate contamination of intravenous drugs – should we be using filter needles?
Lewis Fry, 2015

Maximizing patient safety: filter needle use with glass ampules – NCBI

Glass contamination in parenterally administered medication. – NCBI

Glass Ampules and Filter Needles: An Example of Implementing the Sixth ‘R’ in Medication Administration

What is a filter needle and why do we need to use it?

Glass Ampoules – Risks and Benefits:

About author View all posts Author website

Paolo Broccardo

I help men take control of their testosterone, health and lives. Testosterone Replacement Therapy turned my life around and my goal is to help other men with low testosterone do the same.

2 CommentsLeave a comment

  • Thanks for this information. Today when I picked up my order I got Ampoules instead of the Vials I am used to. It has me really annoyed as there are so many things to worry about regarding the contamination factors with ampoules. I think that I will purchase a sealed vial and transfer them into there, however I still have to take my shot on Monday. I saw on your YouTube channel you spoke about storing the remaining dosage from the amp in the syringe and switching out the needling before administering the shot. My question is, how long can I keep it stored, if my shot dates are 2 weeks in between? Should I take the chance and store it that long? or Just delay my shot until the vial comes?

    • Officially, the doctors will advise you to throw away the remainder. If however, you decide to split and store it and use it, just understand that there are risks associated with that. I have done it in the past, but that doesn’t mean it’s correct or safe. If cost isn’t a major factor for you, then it’s probably best to throw the remainder away.

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