The usual dose of quinine for leg cramps is one tablet at bedtime. The strength of the tablet will be either 200 mg or 300 mg.
Quinine is present in drinks such as tonic water and bitter lemon - try to avoid these while you are on quinine.
Contact a doctor immediately if anyone swallows quinine by accident, or if you take more than the prescribed dose.
|Type of medicine||An antimalarial medicine|
|Used for||Treatment of night-time leg cramps|
|Also called||Quinine bisulfate, quinine dihydrochloride, quinine sulfate|
You may be prescribed quinine for cramps in the leg if the cramps regularly disrupt your sleep, or are very painful. Taking quinine is generally only recommended if other treatments (such as stretching exercises and massaging the affected muscle) have been tried first and not been successful.
Quinine is likely to reduce the number and/or the severity of your leg cramps, but it may not stop them altogether. When quinine is first prescribed it will be done on a trial basis for a few weeks, as it may take this amount of time for you to start to feel the benefit. You can assess how well the quinine is working for you, by keeping a sleep and cramp diary. Make a note of how often you get cramp and how severe it is for a few weeks before you start treatment, and then compare this with episodes of cramp after the start of treatment.
Quinine can sometimes cause side-effects (some of which may be serious) so you should also check for any unwanted effects it is having on you. If quinine helps you then you may be advised to continue with it for a few months. You should, however, consider stopping quinine every three months or so. This is because, in some people, the cramps go away and so the treatment may no longer be needed.
Before taking quinine
Some medicines are not suitable for people with certain conditions, and sometimes a medicine may only be used if extra care is taken. For these reasons, before you start taking quinine it is important that your doctor knows:
- If you are pregnant, trying for a baby or breastfeeding.
- If you have any problems with your eyes, or with your hearing.
- If you have a heart condition, such as an irregular heart rhythm.
- If you have any problems with the way your kidneys work, or any problems with the way your liver works.
- If you have blood in your urine.
- If you have been told you have an imbalance of salt levels in your blood.
- If you have a condition causing muscle weakness, called myasthenia gravis.
- If you have glucose-6-phosphate dehydrogenase deficiency. This is a genetic disorder where there is a lack of an enzyme often known as G6PD. People with this disorder have problems after eating foods such as fava beans.
- If you are taking any other medicines. This includes any medicines you are taking which are available to buy without a prescription, as well as herbal and complementary medicines.
- If you have ever had an allergic reaction to a medicine, or if you have had a bad reaction to quinine in tonic water or any other soft drink.
How to take quinine
- Before you start the treatment, read the manufacturer's printed information leaflet from inside the pack. It will give you more information about quinine and will provide you with a full list of the side-effects which you may experience from taking it.
- Take quinine exactly as your doctor tells you to. It is usual to take one tablet (of either 200 mg or 300 mg) at bedtime. Your dose will be printed on the label of the pack to remind you about what the doctor said. Do not take more than the prescribed amount.
- Swallow the tablet with a drink of water.
- If you forget to take a dose, do not worry, just skip the missed dose and take your next dose on the following evening as usual. Do not take two doses together to make up for a forgotten dose.
Getting the most from your treatment
- Remember to keep your regular appointments with your doctor. This is so your doctor can check on your progress. You may need to take quinine for about four weeks before you feel the full benefit.
- Your doctor will discuss with you the possibility of unwanted side-effects of the treatment. It is important that you let your doctor know as soon as possible if you experience any of the following: impaired hearing, ringing noises in your ear, headaches, feeling sick, or any problems with your eyesight.
- Quinine is present in drinks such as tonic water and bitter lemon. It is probably best to avoid these drinks while you are on quinine.
- Never take more than the prescribed dose. Taking too much quinine can cause serious problems. Also, quinine is dangerous if it is taken by a child, so keep the tablets away from children. If you suspect that someone has taken an overdose of quinine or has swallowed some by accident, you must contact a doctor straightaway. Alternatively, go to the accident and emergency department of a local hospital. Do not delay. Take the container with you, even if it is empty. This is so the doctor knows what has been taken.
- If you buy any medicines, always check with a pharmacist that they are suitable to take with your other medicines. This is because some medicines (such as cimetidine which is taken for heartburn) can interfere with quinine and increase the risk of serious side-effects.
- If you have diabetes you may need to check your blood glucose more frequently, as quinine can affect the level of sugar in your blood. Your doctor will be able to advise you about this.
Can quinine cause problems?
Along with their useful effects, most medicines can cause unwanted side-effects although not everyone experiences them. The table below contains some of the ones associated with quinine. You will find a full list in the manufacturer's information leaflet supplied with your medicine. Although side-effects are uncommon when quinine is used to treat leg cramps, serious side-effects do still sometimes occur. Contact your doctor for advice as soon as possible if you experience any of the following:
|Quinine side-effects ||What can I do if I experience this?|
|Diarrhoea, feeling sick (nausea), feeling weak or confused, 'ringing' in your ears, headache, having a spinning sensation (vertigo)||Tell your doctor as soon as possible|
|Difficulties seeing, such as blurred vision and colour changes||Tell your doctor as soon as possible. Do not drive while your vision is affected|
|Hot and flushed skin, rashes, muscle weakness, increased sensitivity to light||If any of these become troublesome, let your doctor know|
|Difficulty breathing, swelling around your mouth or face||Speak with your doctor straightaway - these are signs of an allergy to quinine|
|Unexplained bleeding, unusual bruising, sore throats or infections||Tell your doctor as soon as possible - these could be signs of a serious blood disorder and your doctor will want to check for this|
If you experience any other symptoms which you think may be due to the tablets, please speak with your doctor or pharmacist for further advice.
How to store quinine
- Keep all medicines out of the reach and sight of children.
- Store in a cool, dry place, away from direct heat and light.
Important information about all medicines
If you are having an operation or dental treatment, tell the person carrying out the treatment which medicines you are using.
This medicine is for you. Never give it to other people even if their condition appears to be the same as yours.
Do not keep out-of-date or unwanted medicines. Take them to your local pharmacy which will dispose of them for you.
If you have any questions about this medicine ask your pharmacist.
Further reading and references
Manufacturer's PIL, Quinine Sulfate Tablets 300 mg; Accord-UK Ltd, The electronic Medicines Compendium. Dated September 2020.
British National Formulary, 81st Edition (Mar 2021); British Medical Association and Royal Pharmaceutical Society of Great Britain, London.