Pyrimethamine and Sulfadoxine (Oral)

If you are about to go to, or have just been to, an area where serious malaria strains were present, then Pyrimethamine and Sulfadoxine is a powerful drug to be prescribed. You should be well aware of all potential side effects associated with taking it.


Pyrimethamine and Sulfadoxine combination is used as a means to treat those suffering from malaria. As well as this, if you live, or are travelling to an area which is at higher risk of contracting malaria, you may be prescribed this drug. There are a few other cases Pyrimethamine and Sulfadoxine may be used, as well as it being prescribed alongside other malaria drugs. However, you should never look to take Pyrimethamine and Sulfadoxine without having first received a doctor's prescription.

Pyrimethamine and Sulfadoxine combination is usually used to prevent more serious types of malaria, whereby other drugs will not be as effective. However, the only problem with this is that it can potentially lead to some more serious side effects from occurring. For this reason, you should never self-prescribe or use any Pyrimethamine and Sulfadoxine you have without first consulting with your doctor in depth to find a correct dose.

Conditions treated

Type of medicine

  • Tablet

Side effects

Pyrimethamine and Sulfadoxine can potentially cause a number of different side effects, some of these are less pleasant than others. Directly below you can find a list of side effects which, if you suffer from, you should seek immediate medical attention.

More common:

  • Soreness or irritation of the tongue
  • Increased skin sensitivity to sunlight
  • Skin rash
  • Fever
  • Less common
  • Hoarseness or a cough
  • Yellow skin or eyes
  • Tarry, black stools
  • Bruising or bleeding sores on lips
  • Unusual weakness or tiredness
  • Vomiting
  • Chest pain
  • Chills
  • Blood in stools or urine
  • Difficult or painful urination
  • Peeling, blistering, loosening or redness of the skin
  • Sores on lips
  • Ulcers, white spots and/or sores in mouth
  • Unusual bruising or bleeding
  • Swelling in upper abdominal area
  • Sore throat
  • Lost appetite
  • Side of lower back pain
  • Pinpoint red spots on skin
  • Muscle pain or cramps
  • Nausea
  • Sore mouth


  • Stomach or abdominal pain
  • Constipation
  • Swelling or puffing around the eyes or of the eyelids
  • Difficulty breathing, wheezing, shortness of breath, or tightness in chest
  • Irregular or fast breathing
  • Burning of the skin, itching or tenderness
  • Front part of the neck becoming swollen
  • Changes in your facial skin color

If you or someone else has overdosed on Pyrimethamine and Sulfadoxine, here are the effects to look for. Again, seek immediate medical attention.

  • Seizures or convulsions
  • Lost appetite
  • Soreness or irritation of the tongue
  • Severe vomiting
  • Severe bruising or bleeding
  • Unsteadiness or clumsiness
  • Trembling
  • Unusual weakness or tiredness
  • A sore throat and fever

As well as the more severe side effects above, there are a number of other effects you could have which are not as severe. In some cases these effects are manageable, but in other cases, they are too unpleasant. If you are suffering from any of the effects below and would like them relieved, you should also contact a doctor. However, do be aware, that they are not as threatening as those above.

More common:

If you have any other side effects not listed here but believe they are related to Pyrimethamine and Sulfadoxine, then you can contact your doctor for guidance.


Below you can find the average dosages that will be prescribed to both adults and children. However, if your dosage differs in any way, then you should not alter what you take based on what you read here. Instead, you should follow your doctor's prescription at all times. All individuals will be prescribed differently, and necessary dosages will be calculated based on your medical condition. It may also be the case that you are on a stronger tablet, or have a higher frequency of taking the tablet. Altering your dose could cause an increased chance of unwanted and potentially harmful side effects.

When treating malaria:

  • Adults and teenagers - Take three tablets in one single dose on the third day of your quinine therapy.
  • Children - Your dose will be calculated by your doctor and is based on body weight.

When self-treating what is presumed to be malaria:

  • Adults and teenagers - Take three tablets in one single dose if you are suffering from a fever and do not have access to medical care.
  • Children aged above two months old - Your dose will be calculated by your doctor and is based on body weight. Typical doses range from ½ a tablet to three tablets all taken in one go.

When preventing malaria:

  • Adults and teenagers - Every seven days, take one tablet. Alternatively, every 14 days, take two tablets.
  • Children aged above two months old - Your dose will be calculated by your doctor and is based on body weight. Typical doses may be ¼ of a tablet to ¾ of a tablet taken once every seven days. Alternatively, it may be ½ a tablet or 1 ½ tablets taken once every 14 days.

It is important that you try and take every single necessary dose. However, if you do miss a dose, then take it as soon as you remember. This is as long as it's not almost time for your next dose. It is important you do not double dose at any time.

It is worth pointing out, that it is rare that Pyrimethamine and Sulfadoxine are prescribed to children aged less than two months old. There is an increased chance of children overdosing, so keep it away from children unless prescribed.

Sulfadoxine is of course sulfa-containing, and as such it is best taken with a full eight-ounce glass of water. Unless otherwise instructed by your doctor, you should also drink several additional glasses of water every day. By drinking this increased amount, you should be able to help avoid other unwanted side effects. This includes, but is not limited to kidney stones. If it causes you to vomit, or it upsets your stomach, then you should take Pyrimethamine and Sulfadoxine with a meal or snack.

If you are taking Pyrimethamine and Sulfadoxine to help prevent malaria, then here is some additional advice when taking it.

  • Your doctor may well get you to take it at least one or two weeks before you leave the country and enter the malaria zone. This gives them chance to look for any unwanted side effects and make any adjustments to your dosage as necessary. If you have a bad reaction, they may change the drug altogether.
  • You must take Pyrimethamine and Sulfadoxine for the full time you are in the malaria zone, as well as four weeks after you leave it. You can't be guaranteed that this will stop you getting malaria, but by following your doctor's instructions as closely as possible, you can give yourself the best chance of avoiding it. If, whilst you are away, or within two months of leaving, you get a fever, then you should contact your doctor immediately.
  • You should try to maintain as much continuity each week with the way you take Pyrimethamine and Sulfadoxine. For example, try and take it on the same day and time each week. This can also help you to avoid missing any doses.

If you are taking Pyrimethamine and Sulfadoxine to help treat malaria, then you need to stick to your doctor's prescription exactly in order to give you the best chance of recovering.

If you are taking Pyrimethamine and Sulfadoxine to help treat self-presumed malaria, then you should also continue to take your other malaria medicine once a week.


Pyrimethamine and Sulfadoxine have the potential of interacting with a variety of different drugs, so you will be required to tell your doctor about all other drugs you are taking. This refers to all prescription, non-prescription, supplements or herbal drugs that you take. If they believe an unwanted interaction may occur, then they could reduce your dosage or alter the drug altogether. In particular, you should be clear to highlight the fact that you take Aurothioglucose as it is not recommended you mix the two drugs.

The following is a list of drugs with which it is usually not recommended to you take alongside Pyrimethamine and Sulfadoxine. However, as mentioned, you may still be able to take the two, albeit with some form of reduced dosages in place.

  • Sulfamethoxazole
  • Live Cholera Vaccine
  • Trimethoprim
  • Zidovudine
  • Methotrexate

Finally, there is the potential of Lorazepam causing increased side effects if used with Pyrimethamine and Sulfadoxine. However, it may be the case that it is necessary to take both. In which case your doctor can advise on any preventive steps that can be taken to mitigate unwanted side effects.

You should also be careful not to take Pyrimethamine and Sulfadoxine alongside other certain types of food, drink and tobacco. Be honest about your typical dietary intake and they can advise you on any necessary changes you should make to what you consume.

It could also be the case that Pyrimethamine and Sulfadoxine will lead to interactions with other medical problems you suffer from. This list could be wide-ranging so you should highlight all past and present medical conditions you have. However, the following is a more severe list of medical problems that you should be open about if you suffer from.

  • Kidney or liver disease. Again, these problems could increase the chance of you suffering from unwanted side effects.
  • Blood or anemia problems. This could cause an increased risk of blood-specific side effects.
  • A history of seizure disorders (like epilepsy. Taking high doses of Pyrimethamine and Sulfadoxine could cause a higher chance or seizures or convulsions.
  • Porphyria. Pyrimethamine and Sulfadoxine could lead to an attack of porphyria.


As already mentioned, this medicine is used to target more serious types of malaria, which means that added caution is usually taken before prescribing it. Your doctor will have a full consultation with you to decide whether it is indeed the best antimalarial for you. A part of this discussion will be to look at any and all allergies you have. These allergies could be towards other drugs, as well as animals, dyes, preservatives or foods.

If your child is aged two months or younger than it is not usually recommended that they take Pyrimethamine and Sulfadoxine. Beyond this, your doctor will properly examine your child to be sure there are as little risks as possible of Pyrimethamine and Sulfadoxine resulting in unwanted side effects.

Just like many drugs, there have currently not been any trials conducted into the use of Pyrimethamine and Sulfadoxine in geriatric patients. However, your doctor is best placed to decide whether or not this is a suitable drug for you. If not, they will have other antimalarials which could be prescribed instead.

As of writing, there have currently not been suitable studies performed into whether or not Pyrimethamine and Sulfadoxine poses an increased risk to pregnant women. Again, your doctor can examine you on a one-on-one basis and decide whether or not it is suitable to prescribe Pyrimethamine and Sulfadoxine. If, whilst taking this drug, you fall pregnant, then you should contact your doctor immediately.

However, if you are breastfeeding, then you should not take Pyrimethamine and Sulfadoxine. Studies performed have indicated that Pyrimethamine and Sulfadoxine can have harmful effects on infants. Instead, you should seek an alternative drug.

If whilst taking Pyrimethamine and Sulfadoxine you experience any of the following symptoms, then you should contact your doctor immediately. They could be early indications of more severe skin problems that will get worse later.

  • A sore throat
  • Sores on your genitals or in the mouth
  • Itching
  • Redness
  • A skin rash

As well as taking Pyrimethamine and Sulfadoxine, there are other preventative measures you should use to help avoid contracting malaria. This includes:

  • Sleep under a mosquito net whenever possible, to avoid being bitten in the night.
  • Mosquitos are present from dusk through til dawn, so during this time, you should cover all exposed skin with mosquito repellant.
  • At the same time, if possible you should try and wear long trousers, blouses, or long-sleeved shirts.

If you are taking Pyrimethamine and Sulfadoxine to prevent malaria, here are some extra guidelines to follow:

  • Where possible, arrange and stick to regular visits to your doctor. These are necessary to track any potential blood problems which you are at a greater risk of developing.
  • Pyrimethamine and Sulfadoxine do have the potential to cause anemia. If this occurs, your doctor will tell you to take leucovorin as a means to clear this up. If this occurs, then take the leucovorin every day whilst you are taking Pyrimethamine and Sulfadoxine and do not miss any doses.
  • Any blood problems that do arise, can, in turn, lead to a higher chance of other infections, as well as bleeding gums and slow healing. For this reason, be careful when using toothpicks, dental floss and toothbrushes. If you are due any dental work, then you should put this off until your blood counts are back to normal. If you have any further questions about maintaining good oral hygiene during this period, you can speak to your doctor or dentist.
  • This drug may also cause your skin to become more sensitive to sunlight. Such exposure could cause your skin to develop a rash, to become red, discolored, to itch or for you to get a severe sunburn. To help avoid this, try and follow the following advice:
  • Try not to be in direct sunlight between the hours of 10 am and 3 pm.
  • Wear a hat, protective clothing, and sunglasses when outside.
  • The sunscreen you wear should be at least SPF 15, and this should be higher if you have a fair complexion. For further advice on suitable types of sunscreen, you should consult your doctor.
  • Use sunblock lipstick with an SPF that is 15 or higher.
  • Avoid using tanning beds, sunlamps or tanning beds.

If you do suffer a severe skin reaction as a result of the sun, then ask your doctor for the best course of treatment. If you are taking Pyrimethamine and Sulfadoxine to self-treat malaria, then you should seek medical attention if your condition does not improve within 48 hours.


You should keep your Pyrimethamine and Sulfadoxine stored in a sealed container, as prescribed by your doctor. You should also keep it away from heat direct sunlight, and moisture as well as keeping it from freezing. Unless otherwise prescribed, you should not allow children to have access to this drug. Once you are done with your course of treatment using Pyrimethamine and Sulfadoxine, you should dispose of any remaining medication in a safe and sensible way as advised by your doctor. Never take any medication that is out of date.


If you are currently suffering from more severe cases of malaria, then Pyrimethamine and Sulfadoxine could be useful in helping to treat you. Similarly, it can be equally as effective at preventing your form contracting it in the first place. However, it is only fully useful if you follow the exact prescription your doctor gives you. By missing doses, you open yourself up to the threats associated with malaria.

There are a number of different types of antimalarial drugs, and Pyrimethamine and Sulfadoxine are one of the stronger ones, meaning it is prescribed for stronger types of malaria. Therefore, you should never-self-prescribe the use of it, and should instead speak to your doctor for the most effective course of action. They can also accurately calculate the safe dosage for you to consume.

Above, you can find information regarding the possible interactions and side effects that can occur whilst you take Pyrimethamine and Sulfadoxine. If you are currently suffering from the more severe side effects, or are uncomfortable with other effects, then do contact your doctor straight away. They may be able to advise methods to reduce those effects and, if possible, could prescribe you an alternative drug.

Last Reviewed:
February 01, 2018
Last Updated:
April 05, 2018