Leg cramps can be a real pain — literally! If you’ve experienced the discomfort of sudden muscle contractions in your legs or feet, you know just how much it can disrupt your sleep and daily activities, and you may be desperate to find relief. 

That quest for relief has led many to turn to an unexpected remedy: tonic water. But does this fizzy beverage really hold the key to alleviating leg cramps? We spoke with Kaylee Jacks, a sports dietitian at Texas Health Sports Medicine, to dive into the science behind tonic water and explore whether it's truly a helpful solution or just an old wives' tale.

Understanding Tonic Water

Before we get into its potential benefits, let's start by understanding what tonic water is. Tonic water is a carbonated beverage that contains quinine, a bitter compound derived from the bark of the cinchona tree. Quinine has been used for centuries to treat malaria, thanks to its antimalarial properties. The Federal Drug Administration (FDA) currently only approves quinine as a treatment for malaria, even though it had previously been included in over-the-counter medication to treat leg cramps prior to 2007. Today, it is primarily used as a flavoring agent in tonic water, giving it a distinctive bitter taste.

The Quinine Connection  

Quinine, the active ingredient in tonic water, has been suggested as a potential remedy for leg cramps due to its muscle-relaxing properties. It is believed to help reduce the frequency and intensity of muscle contractions that cause cramps. However, the evidence supporting the use of tonic water for leg cramps is limited and mixed.

“Some research suggests quinine has anti-inflammatory effects,” says Jacks. “One study found it to reduce levels of an inflammatory molecule, interleukin 1-beta, which is associated with fever. However, many studies that show quinine’s effect on leg cramps often involve relatively high doses of quinine, much higher than what is typically found in a glass of tonic water.”

The FDA limits the content of quinine in tonic water to 83mg/L. Before 2007, the dose of quinine typically prescribed to treat leg cramps was 200 to 300 mg.

“You would have to drink a little over two liters of tonic water to start possibly seeing therapeutic effects,” Jacks explains. “But there are enough documented adverse effects from drinking an excessive amount of tonic water, which, in my opinion, is anything over a liter. In one study, they had their subject drink only tonic water for one day and he experienced a rare blood clotting disorder.”

While that outcome is extremely rare, quinine is not without its risks. In early 2007, the FDA banned all prescription quinine products other than Qualaquin, which is used to treat malaria. The FDA acted in this manner because of a perception that quinine is not effective for this condition and that its risk potential far exceeds its efficacy potential.

It can trigger rare but potentially life-threatening reactions, such as bleeding issues, kidney damage, abnormal heartbeat, or a severe allergic reaction.

However, more common side effects from excess quinine use include:

• Nausea
• Stomach cramps
• Diarrhea
• Vomiting
• Ringing in the ears
• Confusion
• Nervousness

Additionally, there are some individuals who should avoid tonic water or quinine. You should avoid quinine if you:

• Have an abnormal heart rhythm, especially a prolonged QT interval
• Have low blood sugar (because quinine can cause your blood sugar to drop)
• Are pregnant
• Have kidney or liver disease
• Are taking medications, such as blood thinners, antidepressants, antibiotics, antacids, and statins (these medications may not prevent you from taking quinine or drinking tonic water, but you should tell your doctor about these and any other medications you take.)

Hydration and Electrolytes

Another factor to consider when discussing leg cramp relief is hydration and electrolyte balance, which Jacks thinks plays more of a role in tonic water’s potential to reduce leg cramps than the quinine itself.

Dehydration and imbalances in electrolytes like potassium and magnesium can contribute to muscle cramps. Some brands of tonic water contain small amounts of these electrolytes, which might explain why some individuals experience relief from leg cramps after drinking it. However, the levels of electrolytes in tonic water are usually quite low, so it may not be the most effective solution for those with significant deficiencies.

“I recommend making sure you are hydrating enough DAILY with fluids and electrolytes,” Jacks adds. “Electrolytes include sodium, calcium, potassium, chloride, phosphorous and magnesium. There is tons of evidence supporting that adequate fluid and electrolyte consumption can prevent and/or heal leg cramps. You can achieve adequate electrolyte intake through a consistent, balanced diet rich in fruits, vegetables, whole grains, lean proteins (including plant-based proteins like lentils and beans), dairy and healthy fats (avocado/salmon).”

The Takeaway

While anecdotal evidence suggests that tonic water might provide relief for some individuals with leg cramps, the scientific evidence is inconclusive and limited. The effectiveness of quinine in tonic water for alleviating leg cramps remains uncertain, and consuming excessive amounts of quinine can have adverse health effects.

If you're experiencing leg cramps, it's essential to consult with a healthcare professional for a proper diagnosis and to explore appropriate treatment options. Maintaining proper hydration, ensuring adequate electrolyte intake, and stretching regularly are simple steps that may help prevent leg cramps.

“I’m not a big fan of quinine, but if you find that a glass or so of tonic water appears to be helpful for you, based on current evidence, I believe that would be fine,” Jacks says. “But my recommendation is to identify the cause or causes of your leg cramps. This could be, but not limited to, activity during the day (lack of or type of), physical issues, such as needing to stretch/alignment issues, etc., or fluid intake and/or electrolyte imbalance.”

Remember, what works for one person may not work for another. If you decide to try tonic water as a potential remedy, do so in moderation and be mindful of any adverse effects. Ultimately, finding the right solution for your leg cramps may require some trial and error, but with patience and professional guidance, you can discover what works best for you.