Ferrous sulfate is an iron supplement you may use to treat iron-deficiency anemia. You may need ferrous sulfate if you don’t get enough iron through the foods you eat. Ferrous sulfate comes in tablet and liquid form. Side effects may include constipation, stomach cramps and other digestive issues. Only take an iron supplement as directed.
Ferrous sulfate is a type of iron supplement. You normally get all the iron you need from the foods you eat. Your healthcare provider may recommend ferrous sulfate if you don’t get enough iron in your diet. Iron supplements can be especially beneficial for women or people assigned female at birth.
Cleveland Clinic is a non-profit academic medical center. Advertising on our site helps support our mission. We do not endorse non-Cleveland Clinic products or services. Policy
Iron is one of the minerals your body needs to function properly. Your body needs iron to produce hemoglobin and myoglobin. Hemoglobin is a protein in your red blood cells. Hemoglobin helps your blood carry oxygen from your lungs to all your body‘s tissues and organs. Myoglobin is a protein in your muscles and helps supply oxygen to the cells in your muscles.
If you don’t have enough iron, your body can’t make these proteins, and you may develop iron-deficiency anemia. Iron-deficiency anemia is the most common type of anemia. Anemia is a blood disorder in which your body doesn’t have enough red blood cells
Iron-deficiency anemia can occur if you don’t have enough iron in your body. The condition develops when you lack the iron that your red blood cells need. Factors that can lower your body's supply of iron include:
You lose iron when you lose blood. You can lose blood in many ways:
Some health conditions and medications can decrease your body’s ability to absorb iron. These may include:
You may not have any symptoms if you have a mild case of iron-deficiency anemia. Symptoms of more severe cases of the condition may include:
Anyone can develop iron-deficiency anemia, although the following groups have a higher risk:
Your healthcare provider may order a blood test to check your complete blood count. The blood test will measure your hemoglobin and how many red cells are in your body. If these levels are low, your provider can make a diagnosis of anemia.
Depending on the cause of iron-deficiency anemia, your treatment will vary. Your healthcare provider may recommend eating foods that are high in iron. They may also suggest an oral (taken by mouth) iron supplement such as ferrous sulfate. If you can’t take an oral supplement, you may need to get iron through a vein (intravenously).
You can find iron naturally in many foods. Many food products have also been fortified with iron. Iron-rich foods include:
Your body can absorb iron from plant foods better when you eat it with meat, poultry, seafood and foods that are high in vitamin C. Foods that contain a lot of vitamin C include fruits and vegetables such as oranges, strawberries, tomatoes and broccoli.
In addition to eating foods that are rich in iron, you may have to take an oral iron supplement. The benefit of an oral iron supplement is it treats your symptoms by increasing the levels of iron and hemoglobin in your body.
The iron in your body is called "elemental iron." Oral iron supplements contain different amounts of elemental iron. When you choose a supplement, be sure to check the label to see how much elemental iron it contains. A greater amount of elemental iron means your body will absorb more iron.
There are many different types of oral iron supplements. Ferrous sulfate comes in tablet or liquid form:
If your healthcare provider has recommended an iron supplement, use it only as directed. You should take the supplement on an empty stomach. Take your medication at least one hour before or two hours after you eat a meal.
If you’re using a tablet form, swallow the tablet whole. Don’t try to crush, chew or break it. If you’re using a liquid form, measure the medicine carefully. Use a dosing syringe, not a kitchen spoon. You may not get an accurate dose of the medication.
Your healthcare provider may recommend a special diet while you’re taking ferrous sulfate. Follow their instructions precisely. Store the supplement at room temperature, and keep it out of reach of children.
Other instructions to keep in mind:
Iron supplements can cause is constipation, so drink plenty of water. You may need to take a stool softener along with the supplement. Iron supplements can cause several other side effects. These may include:
The side effects of ferrous sulfate supplements are usually temporary. They should go away as your body gets used to the medication.
Your healthcare provider will help you decide what the best iron supplement is best for you. They’ll also tell you how much iron you need to take every day. The best way to take the iron supplement is through two or more doses each day. This way your body absorbs the greatest amount of iron. However, you should take extended-release iron products once a day.
It may take one to four weeks (after you start your iron supplement) before you start to feel better. Continue to watch your symptoms and take note of side effects. If you have any questions or concerns, talk to your healthcare provider.
Your healthcare provider will let you know how long you have to take an iron supplement. After your hemoglobin and iron levels are back to normal, you may need to continue the iron supplement for another six months. You may have intermittent blood tests to measure your iron level.
A note from Cleveland Clinic
Ferrous sulfate is a type of iron supplement that can help you prevent or treat iron-deficiency anemia. Check with your healthcare provider before you start on any supplements. If your provider recommended you start on ferrous sulfate, make sure to follow their guidance closely. Ferrous sulfate has many benefits but it can also cause side effects. Only take an iron supplement for as long as your provider instructed. Taking more iron than your body needs can cause serious health issues.
Last reviewed by a Cleveland Clinic medical professional on 05/24/2022.
Learn more about our editorial process.