Make your own saline solution

Can it be done?
Yes, you can make your own saline solution for contact lenses, washing wounds, or nasal sprays / drops very cheaply because the main ingredients are just water and salt. I make my own saline at home and use it for lenses without any problems whatsoever.

If you want to make your own saline, here's how to do it with some thought towards reducing the risks. The below is written largely for contact lens use, with a heavy emphasis on sterility, but there's certainly no harm in following these steps if you are planning to use the saline for washing wounds or as a nasal spray either. For one thing, you will be able to store a larger quantity of your solution for longer periods of time with greater confidence.

WARNING!
You can damage your eyesight and even cause PERMANENT BLINDNESS if sterility is compromised when using contact lenses. This can happen even when using commercial solutions, but the risks are higher if you manufacture your own saline. Please consider this danger carefully before proceeding. Are you willing to risk something as precious as your eyesight? Unless you are very confident in your procedure and supplies, or have good reason to take the risk (emergency situation, etc) don’t do it! Every year, many contact lens wearers develop a condition called acanthamoeba keratitis, caused by a common environmental microbe infecting their corneas. Acanthamoeba is found in tap water, swimming pools, the sea, soil, air, and bottled water. It is not inconceivable that it has colonised your bottle of distilled water or your saline solution. If not treated promptly, an acanthamoeba infection can lead to months of corneal inflammation. In some cases the damage cannot be reversed.

I urge you to familiarise yourself with this subject and good lens-care practice by reading this page.

I proceed from this point on the basis of believing that potentially dangerous information will always be offered somewhere on the web, and by providing it here I can at least include some basic precautions.

Supplies
Buy some distilled (or de-ionised, or de-mineralised) water. You should be able to find it with the laundry supplies in your supermarket (it's used for steam irons), in a hardware store, or an auto store (for topping up car batteries). I suggest buying at least a litre or a quart, and preferably twice this much. It's cheap stuff: around 2-3 dollars for 2 litres (half-gallon) here in Australia. Is it sterile? I don’t know. In theory it should be, but it all depends on how it is made and packaged. Some distilled water manufacturers explicity state that their product can be used for contact lens care, so one would assume that such brands are sterile, but as for others, you will be taking a risk. That risk can be reduced by boiling the distilled water when you get it home, and letting it cool while covered, but you’ll need a very clean stainless steel or glass pot, and maybe some sort of funnel for re-filling your container. The funnel will probably not be sterile. Maybe you could rinse the funnel with methylated spirits or rubbing alcohol and let it dry just before using it.

The other supply you need is salt. The ideal source is laboratory grade sodium chloride, available through a lab supply company or perhaps a friendly chemist. Next best would be plain cooking salt, as opposed to table salt. Table salt, and even some brands of cooking salt, contain silica-type minerals added as an 'anti-caking agent'. Silica is exactly the sort of insoluble gritty stuff you don't want in your solution. The cooking salt should probably be plain rather than iodised (though I have used the latter myself), as I can't say what long-term effects, if any, the trace quantities of iodine might bring about. To the best of my knowledge, dry, crystalline salt is a hostile environment for microbes that are likely to trouble you in this context, and is of itself certainly not an acanthamoeba risk. However, I am not an expert, and who knows for sure? Not me.

If you can find a clean, sterile container that holds a litre or a quart, this will be handy too. To really give your containers a thorough sterilisation, use a solution made with sterilising powder from home brew or winery supply shops. However, you'll have to use distilled water to rinse it out completely. Several small rinses are much more effective than one large rinse. You could use a well-cleaned plastic soft-drink bottle as your main storage container. At the very least, rinse it well as soon as the soft drink is finished, first with water that has been well boiled and cooled enough so as to not melt the plastic, and then give it a small final rinse or two with some fresh distilled water.

Measurements
Now comes the hard part: approximating the correct amount of salt. You are aiming for 9 grams per litre, which makes what we want—so-called ‘normal saline’. If you have access to laboratory or jeweller's scales you'll be laughing. You can buy electronic jeweller's scales fairly cheaply on ebay these days. Otherwise, use a teaspoon measure of the kind that is used for cooking. Make sure it's clean and sterile (boiling water and steam are good sterilisers). A teaspoon holds about 5 mls, so allowing for the density of salt, I find that a very slightly heaped teaspoon is perfect for a litre of water. A quart is close enough to a litre that you don't have to worry if that's what you have—just make sure it's a very full quart.

As you can see, this is all quite rough and approximate but I've found that it doesn't matter. You don't need precision, and your eyes (or nose) won't feel the difference. It's better to err on the side of a weaker solution if anything, because too much salt will make your eyes sting slightly whereas too little will only produce a vaguely uncomfortable suction until the osmotic pressures equalise (like the feeling of having distilled water or tap water in your eyes, but much less so). If you find that you've made a solution that's too strong, add more distilled water (which is why it's nice to have some spare).

Storage, procedures and precautions
Pay attention to the way your lenses feel in your eyes. If you start to notice any persistent scratchiness or eye pain, unusual dryness or anything out of the ordinary, go to your optometrist/opthalmologist immediately. Such symptoms could indicate the early stages of a dangerous infection. If you think I am being alarmist, read the first letter below.

Keep the solution in a dark place and/or a dark bottle so that algae don't grow in it, which they definitely will when light is available (even if you can’t see them at first). Keep the lid tight. Don’t touch the rim against any surfaces when pouring or filling. I suggest refilling smaller squirt-bottles and using these on a day-to-day basis. You can often prise the cap off a commercial saline or disinfecting solution bottle and reuse it repeatedly as long as you maintain its sterility—but that’s the key. Sooner or later your plastic squirt-bottle will become infected, so you’ll have to fill it regularly with something like the home-brew sterilising mix, or possibly hydrogen peroxide, followed by plenty of rinsing with sterile saline. Don’t assume it will stay sterile on its own. Keep the caps and bottle tops away from surfaces. Open the bottles only briefly.

Don't use home-made saline if you're disinfecting your lenses with heat. Commercial salines are pH-buffered. If you cook your lenses in a slightly acidic solution repeatedly, it will probably damage them (I did this a long time ago when heat disinfection was popular). Remember also that your home-made saline solution is not actively sterilised. It has no preserving agent in it. Take the proper precautions when preparing and storing it, and it might be fine for rinsing your lenses, but certainly not for your daily sterilisation. You will still need to buy and use a commercial sterilising solution. Use fresh steriliser on your lenses every night.

By employing your saline solution as a final rinse, you can wash off the overnight sterilising solution and spare your eyes from exposure to chemicals. Personally, I don’t like to put those fancy multi-purpose solutions into my eyes, despite the manufacturers’ claims that they are safe.

Should your lenses, lens case or fingers come into contact with tap water, you risk infection. Although it is not recommended, I have always rinsed my lenses in tap water, but I clean them thoroughly and am very careful to sterilise them overnight afterwards. I always clean my fingers with soap and running water, then rinse them with saline before handling the lenses to put them in my eyes. I don’t know if this is good procedure, but it has worked for me for a long time. The site recommended at the top of this page says that you should dry your fingers, before handling your lenses, but with what—a hand towel that sheds lint?

I also minimise my consumption of sterilising solution by choosing lens storage cases with small, rounded chambers. Lens supply companies like to produce big tubs for you to store your lenses in because it forces you to use heaps of their product. Two or three drops per lens is about enough to cover mine in their tightly profiled cases. It might be hard to find such compact lens cases these days. Recent examples that I have been given by my optometrist have rounded profiles, but are somewhat cavernous.

Lens cases should be cleaned frequently on the inside and outside—they can become grotty over time and turn into serious infection risks themselves.

When you get to the bottom of your main saline storage bottle, throw out the dregs and rinse the bottle well before mixing up the next batch. Cooking salt is not totally pure, and insoluble bits tend to sink to the bottom. You should sterilise both the main storage bottle and the daily squirt bottle between refills.

Finally
I make no claims as to the safety of these procedures. Assess this material for yourself and follow these instructions at your own risk. If you ignore the dangers and do choose to make your own saline, use it externally only (don't go injecting anyone with it). I stress that I am not an expert and I am not recommending anything here by implication or otherwise, except for the over-riding importance of safety. This page, like any other on the web where homespun formulations are offered, puts you, the reader, in the position of having to carefully consider and bear the attendant risks. Don't take that position lightly.

Did I mention that cleanliness and sterility are extremely important?

Here's a couple of letters I've received:

Hi there Craig, I am fully supportive of DIY stuff, but I suggest that you perhaps make your warning blurb regarding making your own saline solution a bit more threatening. I decided that it makes more sense to make your own saline solution about a month ago. Here is my stupid story: After a bit of research throughout various forums/websites/home health books, I made my own solution using distilled water and non-iodized salt. Things were going along fine, but I noticed that my eyes were drying out a bit sooner than normal with my 2-week type Acuvue Oasys contacts that normally last around 2-months without discomfort. After a night involving some beer, I was walking with my girlfriend to the bus stop and decided, "this is it, these contacts are through" and took them out and disposed of them. The next morning, my left eye was rather pained and I figured that I should get fully rehydrated and visit some sort of health professional the next day if things didn't improve. Needless to say, they didn't and aforementioned health professional prescribed an antibiotic eyedrop. After a few days of using said eye drop, my eye pain grew from bad to rather terrible. I visited the health professional again and was told, "You have a very serious and dangerous infection in your eye, you need to go to the hospital immediately." I did so, and was prescribed a variety of fortified antibiotics that had to be specially concocted just for me. After 2 weeks of serious and intense battle with the bacteria with a strict regimen of eyedrops, I am left with a scar on my cornea that may or may not ever get better without some sort of surgery. In closing, I'd recommend that you mention something to the effect of "if you notice any irregular eye pain or maladies go to an opthalmologist immediately" and perhaps others can be spared the pain and possible permanent corneal damage that I have sustained. I am 24 and otherwise in perfect health despite myopia. Take care and best regards, GR

On the other hand, Vanessa writes: Just read your Make Your Own Saline Solution page. Although I find your safety warnings right on the money, the letter from GR, the fellow who had the bad infection, warrants a closer look. This guy is wearing lenses for TWO MONTHS that are designed to be worn for two weeks! In my view it is almost inevitable that he would experience problems such as an infection. Additionally, he removed his lenses while walking down the street, presumably without washing his hands first. In the interests of frugality, I also wear my Acuvue Oasys lenses longer than two weeks, but as it gets close to the end of 4 weeks I find that they are becoming uncomfortable. I realise that everyone is different, but two months really seems to be pushing it. So although I applaud your necessary warnings I think, in reading his letter, that we have to be careful not to jump to the conclusion that his infection was caused by the saline.

Another letter raises an interesting idea:

I have been making my own sterile saline for about 20 years now with no problems. As you mentioned, sterility is first and foremost. A good sterilizer is a few drops of colloidal silver in the bottle, after all other sterilizing has been done. John.

I have long wondered whether colloidal silver might be the perfect way to sterilise home-made saline. Colloidal silver solution can be purchased online or in health food stores (you can even find instructions on the web for making your own colloidal silver too, but you need to be handy with electrical stuff). Safety concerns have been raised (see here for example), but these seem to relate to a condition called argyria which develops after long-term ingestion of silver solutions, and would not apply in this case.

A question about Polihexanide:

Dear Craig, I was thinking to do my own saline solution, which I use to put some drops in my eyes, for wetting the eyes or "washing" them. I found in the pharmacy an "optical saline solution", but when I got home an read the composition content I found that it contains Polihexanide 0.00005% and "no salt" (NaCl). I read your website on Saline Solution, and decided to ask you, if you think that the Polihexanide 0.00005% can be dangerous if droped into the eyes?

I'm amazed that commercial saline solution can somehow involve 'no salt', but as for Polihexanide, it seems like the risks are very low, but not zero. See the this link. Personally, if I had a choice I would avoid putting known carcinogens in my eyes if I didn't have to. You never know what kind of synergistic or idiosyncratic effects might come into play.