How Stable Are Nitroglycerin Tablets After Being Opened?

Summary: Nitroglycerin tablets are lifesavers for millions of people worldwide but few of those patients realize their nitroglycerin begins to break down and lose potency as soon as the bottle is opened.  You should never carry nitroglycerin tablets that were opened six months or more ago.  Also, buy nitroglycerin pill holders on necklaces and for each set of car keys to have handy when you might need them most.

Dear Curtis: I was prescribed nitroglycerin for my heart recently and the nurse told me on the way out of the office that the nitroglycerin starts decomposing due to the oxygen as soon as I open the bottle and it probably isn’t as effective in as little as 30 days.Is that true?  Secondly, I put a couple of tablets in a little container on my keyring do you think those will break down faster?

Yes, it is true that nitroglycerin (NTG) begins to break down the minute the seal is broken on the bottle.  But, your nurse was wrong.  It’s not 30 days – it’s 6 months.  Now, there are some exceptions to this rule.

Nitroglycerin Tablets

On every bottle of medication that comes from a drug manufacturer they put two things: a Lot number and an expiration date.  Because a pharmacy simply relabels the little bottles of nitroglycerin you should be able to see an expiration date on the bottle.  If not, call the pharmacy and ask them to look on the box that the nitroglycerin came in.

The reason this is important is because sometimes pharmacies get products from their wholesalers that are ‘short dated’.  This means that instead of the expiration date being out one year or more – the bottle may expire in 5 months.  This isn’t worth much to the pharmacy because they may not use the whole bottle by then and would be left with a half bottle of useless, expired drugs.  So, most pharmacies will catch this.  But, that’s the exception I was talking about.  The only way to find out is to know the expiration date on the bottle or the box that the nitroglycerin came in.  Otherwise, get a new bottle of nitroglycerin six months from the day you opened the bottle.

Now, about putting tablets in a container on your key ring.  First of all, you’re (as surprising as this might be) way ahead of most patients who are on nitroglycerin.  Theyseem to think that they’ll just remember to take their nitroglycerin bottle with them wherever they go.  Of course, the opposite occurs and – as Murphy’s Law would have it – if you’re going to have an emergency you’ll likely have it when your nitroglycerin is nowhere to be found.  So, rather than just recommending a key ring take it one step further.

Purchase a nitroglycerin key ring for each set of keys you regularly use and also but a necklace pill holder that you will always have with you.  Not only does this cover you in all emergencies but these little pill holders are not that expensive.  Five to ten bucks for each holder.  Additionally, just buy the necklace pill holders and if you want to put them on your key ring just remove the necklace part and latch onto your keys.  When you purchase one of the pill holders make sure they are all metal, have a rubber O-ring to keep out any moisture and a nice touch is to have a food grade plastic lining inside.  But, the biggest thing is to make sure they are air and water tight and that they are specially designed just for nitroglycerin.  Don’t buy those cheapo plastic holders.  They fluctuate in heat too much and are prone to letting in moisture.

But remember, just like the first part in your question, you have to change out the tablets before they start losing their potency.  Nitroglycerin tablets, even if you don’t have insurance, are not that expensive so changing them out every six months (or earlier) is a small price to pay for the piece of mind they bring you.


  1. Sandra Cowan says:

    Recently, my husband started carrying Nitroglycerin tablets. If he carries them in an approved bottle on his key ring, the key ring goes in his pocket next to his body. If he wears a necklace, he would wear it under his shirt again next to his body. Forget carrying a purse because that’s exactly what he would do – forget it and leave it someplace.

    Any suggestion!

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