tonic water is safe, a glass of gin and tonic with ice and a lime slice

In the heat of a summer afternoon, a tall cold glass of tonic water can seem very appealing. It may even have health benefits, such as warding off nighttime leg cramps. But if you get carried away and turn one glass into two or three, is that dangerous? (Mind you, we are talking only about the tonic WITHOUT the gin. Three alcoholic drinks have clear dangers.) How much tonic water is safe for you to drink?

Unexpected Advantages of Drinking Tonic Water:

Q. I am normally a mosquito magnet. By this time of year I would usually have dozens of bites and the itching would be intolerable. I would turn into a bloody mess from constant scratching.

This year I have been drinking tonic water two or three times a day and I haven’t had a mosquito bite in weeks. As an added bonus, I haven’t experienced leg cramps while cycling. In hot weather I used to cramp up after two or three hours of hard riding.

Is there a limit on how much tonic you can drink before overdosing on quinine? I have read in your column that too much could be dangerous, but how much is too much? How much tonic water is safe?

Tonic Water as a Source of Quinine:

A. Doctors used to prescribe quinine pills to prevent leg cramps. The standard dose was between 200 and 300 mg of quinine.

The FDA banned quinine for this purpose but continues to allow it in tonic water. A liter normally has 83 mg of quinine. An eight-ounce glass would therefore have roughly 20 mg, about one-tenth the lowest dose doctors prescribed for leg cramps. Even three glasses daily should be OK as long as you are not sensitive to quinine.

Some susceptible people develop a dangerous blood disorder after even small doses of quinine. For them, no amount of tonic water is safe! Symptoms of quinine toxicity include digestive upset, headache, ringing in the ears, visual disturbances, skin rash and arrhythmias.

It makes sense to pay attention to your reactions, as the threshold for problems such as tinnitus may vary from one person to another.

Join Over 140,000 Subscribers at The People's Pharmacy

Each week we send two free email newsletters with breaking health news, prescription drug information, home remedies and a preview of our award-winning radio show. Join our mailing list and get the information you need to make confident choices about your health.

  1. Muriel

    I drink tonic water most of the day when I am thirsty but I feel so ill I can hardly put one foot in front of the other I also have lots of pain in my legs during the night .i am going to stop drinking it and see what happens . What have this space

  2. Andrea S
    South Carolina

    I started tonic water to reduce leg cramps at night. It didn’t help much for the leg cramps but to my surprise it greatly helped my problem with urinary incontinence!

  3. Jerry
    South Carolina

    My Doctor told me to start drinking Tonic Water for cramps. I had them in my sides, my legs, feet and hands. Since I have been drinking diet tonic water, I have not had a cramp. I drink two bottles one in the morning and one before bed. Each bottle contains 8.5 fl. oz. (250ml.) I hope this is o.k because I am a firm believer in Diet Tonic Water.

  4. LVT

    I suffered really badly from night cramps and started drinking tonic water. I take a large glass up to bed with me. I drink some before sleeping and some during the night if I wake. I drink diet tonic as I am trying to avoid sugary drinks. It has certainly stopped the cramps in legs and feet. I don’t seem to get any side effects, even when I drink it during the evening.

  5. Tom
    New Jersey

    I am 82, reasonably good health. I sip diet water about ten time a day, as a thirst quencher. [when I’m home] total about 1 pint.

    I don’t believe it is causing any problems. but I still get lower leg cramps during the night when in bed. tho I tend to blame that on poor circulation typical for my age.

  6. Lori

    When really stressed i’ve had muscle twitches of my eyelids. My eye doctor told me to drink 8 ounces of Tonic Water once daily. It works.

    • Yolanda
      Horsham, UK

      I was suffering with severe muscle twitching in my left eyelid for many weeks. Not knowing who to go to I visited my optician, Dr and also tried a relaxing Indian Head massage therapy. My eyesight was fine, my Dr could find no reason for the twitching, and the massage did not work. I was then sent an article about the benefits of drinking Tonic Water to alleviate the symptoms and it worked almost immediately, certainly within hours! Definitely works!

  7. Dale

    I have drank tonic on a regular basis for many years, and as I get older, I’m having issues with the high fructose corn syrup, so I started looking for natural tonic, which is hard to find and is expensive.

    I did find a product at Fresh Market that was reasonable. There are natural tonics out there on the internet. I don’t drink diet tonic either. As far as leg cramps go, I have had issues with that but I take a supplement, which has magnesium, potassium, calcium. I also use a homeopathic leg cream, which works great.

  8. J. David Auner
    Springfield, MO, USA

    Hemolytic anemia is a rare problem with quinine and quinidine – but could happen with even small exposures.

    • Aida

      Fever-Tree elderflower tonic water made with natural quinine, no artificial sweetners, flavorings or preservatives. A little more expensive then other brands, but…..I’ll have a vodka tonic once in awhile with 5 ounces tonic water.

    • Mary
      Lakeland, FL

      If you have Publix (FL) grocery stores, they have their own brand regular or diet. It works great. I use an over the counter lidocaine(4%) / menthol (1%) potion rubbed on over areas of severe cramping along with it for faster and longer relief. I am finally getting more that a couple hours sleep.

  9. Marilyn

    Why not take magnesuium for leg cramps? I take 250 mg but most people can safely take 500 mg per day without problems. Many people are magnesium defficent and don’t know it anyway.

  10. Virginia

    What has happened to paregoric for stomach cramps? Even my pharmacist isn’t familiar with this drug that was once OTC – then by prescription, then not available at all. There has never been an OTC product as effective for relieving pain.

    • Steve

      Paregoric is an opiate that historically was widely abused by addicts. It’s most common usage was to treat diarrhea but was pretty much sidetracked in favor of Imodium. As part of the general crackdown on drugs which can be abused, it’s been heavily discouraged, and is available only by prescription.

  11. Katharine

    On quinine and tonic water: some people (including myself) find that this is a trigger for atrial fibrillation. I would experience an a fib attack about an hour after entering a restaurant, which was about 50 minutes after imbibing my customary gin and tonic. After reading that quinine can be an a fib trigger, I stopped the drink and have not had an attack since then.

    • Cindy
      Seattle, WA

      This is a reply to Katharine, who warns that tonic water is a trigger for A-Fib (at least for her) and says people should be aware of this. Well, I had A-Fib for about 2 years (now resolved with the help of surgery), and I sure don’t want it to return.

      Since I like tonic water a lot, I IMMEDIATELY did a Google search for “Tonic water and A-Fib.” I must say, I found no references at all for tonic water being a trigger, but FOUR references that said it was used in the TREATMENT of A-Fib, i.e., that it would help RESOLVE it.

      I thought this was so interesting that I dug this PP email out of the trash and did this comment. Anyway, I now feel better about the quinine water. Cheers!

  12. Amy

    A friend who has Parkinson’s drinks tonic water to reduce leg cramps. When I tore the vitreous in my left eye and developed muscle spasms in my eye, she suggested thatI start drinking tonic water to reduce the muscle spasms. It worked for me! Initially, I had to drink 2-3 glasses per day but was able to reduce to 1-2 glasses. It has taken most of the past year for the tear to heal. I’m not drinking tonic water every day, but I keep it around for days I feel more pressure in my eye.
    I worried a little about the quantity I drank initially, but the pain was so intense and unbearable.

What Do You Think?

We invite you to share your thoughts with others, but remember that our comment section is a public forum. Please do not use your full first and last name if you want to keep details of your medical history anonymous. A first name and last initial or a pseudonym is acceptable. Advice from other commenters on this website is not a substitute for medical attention. Do not stop any medicine without checking with the prescriber. Stopping medication suddenly could result in serious harm. We expect comments to be civil in tone and language. By commenting, you agree to abide by our commenting policy and website terms & conditions. Comments that do not follow these policies will not be posted.