Oedema, also known as dropsy, is the medical term for fluid retention in the body.

The build-up of fluid causes affected tissue to become swollen. The swelling can occur in one particular part of the body – for example, as the result of an injury – or it can be more general.

This is usually the case with oedema that occurs as a result of certain health conditions, such as heart failure or kidney failure.

As well as swelling or puffiness of the skin, oedema can also cause:

  • skin discolouration
  • areas of skin that temporarily hold the imprint of your finger when pressed (known as pitting oedema)
  • aching, tender limbs
  • stiff joints
  • weight gain or weight loss
  • raised blood pressure and pulse rate

Types of oedema

Oedema can occur anywhere in the body but it’s most common in the feet and ankles, where it is known as peripheral oedema.

Other types of oedema include:

  • cerebral oedema (affecting the brain)
  • pulmonary oedema (affecting the lungs)
  • macular oedema (affecting the eyes)

Idiopathic oedema is a term used to describe cases where doctors are unable to find a cause.

What causes oedema?

Oedema is often a symptom of an underlying health condition. It can occur as a result of the following conditions or treatments:

  • pregnancy
  • kidney disease
  • heart failure
  • chronic lung disease
  • thyroid disease
  • liver disease
  • malnutrition
  • medication, such as corticosteroids or medicine for high blood pressure (hypertension)
  • the contraceptive pill

Oedema that occurs in the leg may be caused by:

  • a blood clot
  • varicose veins
  • a growth or cyst

Oedema can also sometimes occur as a result of:

  • being immobile for long periods
  • hot weather
  • exposure to high altitudes
  • burns to the skin


Lymphoedema is a common cause of fluid build-up in the body’s tissues. It occurs when the lymphatic system is damaged or disrupted.

The lymphatic system is a series of glands (lymph nodes) around the body connected by a network of vessels similar to blood vessels. Fluid surrounding body tissues usually drains into nearby lymph vessels so it can be transported away and back into the blood.

However, if the lymphatic vessels are blocked, excess fluid cannot be re-absorbed and will build up in tissue.

Read more about lymphoedema.

Treating oedema

Oedema usually clears up when the underlying condition causing the fluid imbalance is diagnosed and treated.


Your doctor may recommend some things you can do yourself to reduce fluid retention, including:

  • losing weight (if you are overweight)
  • taking regular exercise, such as walking, swimming and cycling
  • raising your legs three-to-four times a day to improve your circulation
  • avoiding standing for long periods of time


Diuretics are a type of medication that may also be prescribed to help reduce fluid build-up. They work by increasing the amount of urine you produce.

Not everyone can use diuretics and in some cases they can make things worse. They are mainly used to treat people who develop oedema as a result of heart failure.

What Is Edema: Tips For Treating Edema In Plants

Ever have one of those days when you feel a little sluggish and bloated? Well, your plants can have the same problem — they retain water just like people do when conditions are not right. Edema in plants is not a serious disease and it’s not a symptom of a bacteria, virus or insect infestation. Common causes of plant edema include over watering and improper fertilization; it’s easily curable if caught early.

What is Edema?

Edema, or oedema, is a type of abnormal water retention in plants, often influenced by the plant’s environment. Favorable conditions actually encourage edema in many cases, since affected plants already have a fair amount of water in their systems, providing them with more can just encourage them to gorge on liquid. Any time the plant takes up water faster than it transpires, edema becomes a risk.

Signs of edema plant disease vary between susceptible species, but often include bumps, blisters or water-soaked areas on the undersides of leaves. These areas may expand and become corky, but in other plants, curling and distortion are common. White, crusty eruptions may form along the leaf veins or gall-like structures can develop under leaves with yellow corresponding spots on the upper leaf surface.

Treating Edema

Because it’s not a disease, there are many ways to treat edema, depending on the cause. Your job as gardener is to figure out what’s causing your plant’s problem and correct the situation. If your plant has edema, first adjust your watering habits. Most plants should never sit in water, so remove those saucers and make sure that big pots are draining well.

Roots tend to absorb water faster when the water is warm and the atmosphere is cool, so wait to water until the sun is up in the morning whenever possible. Indoors, humidity can have a considerable influence on edema; improving air circulation around plants will help reduce humidity into safer ranges.

Increasing the light intensity is helpful for many plants with edema, but be sure not to cook them by moving them too quickly into brighter light. Make these changes gradually, over the course of a week or two, slowly leaving the plant in brighter light for an increasing length of time, until it no longer wilts in response to the sun.

Lastly, make sure you’re fertilizing your plant properly. Plants with low available potassium and calcium can be more susceptible to edema. If cultural conditions seem correct for your plant, a soil test may be needed. Adjusting the pH can make more nutrients available, or you may need to add more of the nutrients that are lacking.

Edema and Intumescence

Edema (oedema) and intumescence are not caused by pathogens and are not transmissible from one plant to another. They are physiological responses to specific stimuli. These two conditions are often mistaken for one another; however, research indicates that they are caused by different environmental factors and plant physiological responses. While edema is considered to be the result of an imbalance in water relations within a plant, intumescence is associated with low ultraviolet-B (UVB) radiation. Both of these conditions are commonly seen in the spring during prolonged stretches of cloudy weather.

Intumescence and edema both appear as small, bumpy protrusions on the surface of leaves, petioles, and stems of affected plants. The bumps may be green, white, or tan depending on the host and severity of the condition. Symptoms may be mistaken for galls formed by eriophyid mites; however, mites will be absent. Edema is most typically observed on the lower leaf surface, while intumescence may be seen on lower or upper surfaces. Symptoms of edema occur on leaf tissue between veins, while intumescence can occur in between or directly on top of the mid-rib and major leaf veins. Plants susceptible to edema include ivy geraniums, sweet potato vine (ipomoea), tomatoes, peppers, begonias, cacti, ferns, palms, pansy, cleome, and cole crops like broccoli, cabbage, and cauliflower. Some succulent plants such as jade and peperomia are also sensitive to conditions which lead to the development of these symptoms although almost any broadleaved plant may be affected. Intumescence is commonly seen on sweet potato vine (ipomoea), tomatoes, peppers, kale, Cuphea, and Thunbergia. Both edema and intumescence are temporary reactions, and once the weather impoves, new growth will be asymptomatic.

Edema on Ivy Geraniums

Photos of symptoms on various plants – New England Greenhouse Update Photo Gallery

Edema blisters form on ivy geraniums when water and solutes build up underneath or possibly within cells, causing the epidermal cells to stretch and collapse. The cells do not rupture as was previously thought. Symptoms of edema appear as bumps or blisters initially on the undersides of lower or older leaves on a plant. They may then turn brownish or tan and become corky. Severely affected leaves will often turn yellow and fall off the plant. The corky spots sometimes resemble spider mite or thrips damage. To rule out pest damage, growers are advised to use a handlens and check carefully on the undersides of leaves along midveins for spider mites and in growing points for thrips. Mildly affected plants often recover from edema, putting out symptomless new growth in late spring and early summer. Severely affected plants may drop significant numbers of leaves and have badly distorted remaining leaves. These plants are probably not worth saving as they will not recover in time for sale.

Cultural Recommendations for Management of Edema

Several studies have reported that edema on ivy geraniums occurred when the growing media remained warm and moist and the greenhouse air was cool and moist. The plant roots absorbed water at a faster rate than was transpired through leaf tissue, causing leaf cells to rupture. This rupturing of the leaf epidermis and the inner cells is believed to cause the raised, blistered appearance on the underside of the leaf.

Suggestions for managing edema include:

  • Use well drained growing media.
  • Increase light exposure by properly spacing plants.
  • Avoid overfertilizing, especially of slow-growing plants.
  • Water prudently (not too much, not too little) during extended periods of low light and cool temperature.
  • Reduce humidity by venting the greenhouse first thing in the morning, even if that means turning up the heat. See “Reducing Humidity in the Greenhouse” in the Nov./Dec.2003 issue of Floral Notes.
  • When using containers that have snap-on saucers, delay putting the saucer on until the crop is nearly finished.
  • Place varieties with similar growth vigor on each irrigation line or section, again to eliminate overwatering.
  • Select ivy geranium cultivars that are less susceptible to edema.

Table 1. Ivy geranium cultivars categorized by susceptibility to edema as published in 1993 in Geraniums IV .

Table 1. Susceptibility to edema

Most susceptible Intermediate Most resistant
Amethyst Madeline Crozy Sugar Baby
Yale Cornell Double Lilac White
Balcon Princess Spain Salmon Queen
King of Balcon Pascal Sybil Holmes
Balcon Imperial Rigi Galilee
Balcon Royale Rouletta
Beauty of Eastborne

Table 2. Susceptibility of ivy geranium varieties to edema, grown in the Rutgers University greenhouses in 1995. The plants were visually rated on a scale of 1-10 with 1 being highly susceptible and 10 indicating few symptoms. * These plants were grown and evaluated in a glass greenhouse.

Cultural Recommendations for Management of Intumescence

  • Increase light exposure by properly spacing plants.
  • Delay application of shade cloth or shade paint in spring.
  • Select cultivars that are less susceptible to intumescence.

Intumescence Susceptibiltiy of Ornamental Sweet Potato Cultivars

In recent research by Kansas State University, ornamental sweet potato cultivars were screened for susceptibility to intumescence. Out of 36 cultivars tested, 19 did not show any symptoms of intumescence development. According to the research, susceptible cultivars included ‘Blackie’, ‘Black Heart’, ‘Desana Bronze’, ‘South of the border chipotle’, ‘Sweet Caroline Bronze’, ‘Sweet Caroline Sweetheart Red’ and ‘Tricolor’. For information see the article: Intumescences: Further Investigations into an Elusive Physiological Disorder in the September 2014 issue of Greenhouse Product News Magazine.

Compiled 11/04, Revised 2013, 2014, 2019


Edema pustules on the underside of a geranium leaf

Ann Joy and Brian Hudelson, UW-Madison Plant Pathology
Revised: 2/17/2012
Item number: XHT1116

What is edema? Edema (or oedema) is a physiological disorder that frequently occurs in houseplants, greenhouse plants, and other plants sheltered under plastic. This disorder also affects field-grown vegetable crops under certain environmental conditions. Edema is often a cosmetic problem, but in extreme cases, edema can ruin a greenhouse crop and cause severe economic losses.

What does edema look like? Small translucent, fluid-filled blisters form on the undersides of mostly older leaves, often beginning at the leaf margins. Blisters can also occur on stems and occasionally on flowers. When observed against the light, edema lesions are lighter in color than the surrounding leaf tissue. The blisters may increase in size or merge, burst, and then scar, turning tan in color and corky in texture. Some or all leaves may eventually shrivel or roll, and fall off. Extensive blistering and scarring may limit the plant’s ability to photosynthesize.

Where does edema come from? When the soil is warm and moist, water absorbed by a plant’s roots may exceed the water lost through a plant’s leaves. Conditions preventing effective water loss include high relative humidity, low light intensity, cool air temperatures and poor ventilation. Periods of cloudy weather, or an increase in relative humidity resulting from cooling air temperatures, can make plants susceptible to edema. Edema has also been associated with the use of oil sprays that interfere with normal water loss.

How do I save a plant with edema? Edema is typically not fatal, but will make plants less attractive. To limit problems with edema, water less frequently in cloudy periods or under low light intensity. Water in the morning so that the soil in which plants are potted will drain by nightfall when cooling temperatures can lead to increased relative humidity.

How do I avoid problems with edema in the future? Use a growth medium that drains well. Reduce relative humidity near the leaf surface by increasing plant spacing and air circulation. Increase light and air temperatures to help increase normal water loss. Water less frequently during cool, humid weather. Empty standing water in saucers under pots 30 minutes after watering.


Tags: disease, indoor Categories: Flower Problems, Vegetable Problems


Edema related to circulation (vascular), heart or liver problems

A variety of diseases can cause edema. Most of the time, the edema is not a serious illness, but it may be a sign for one. Here are some examples:

Venous insufficiency can cause edema in the feet and ankles, because the veins are having trouble transporting enough blood all the way to the feet and back to the heart. This means that it gathers in the legs, and fluid is forced out of the blood vessels into the surrounding tissue. Edema can also be caused by varicose veins.

Congestive heart failure can cause both peripheral edema and abdominal edema (ascites). This is because the heart is too weak to pump blood around the body properly, so the blood gathers in front of the heart. Because of this, and due to the increased blood pressure in the veins, fluid seeps out into the surrounding tissue. This may cause swelling in the legs or a build-up of fluid in the abdomen. If the person spends a lot of time lying down, the edema might show up on his or her back (called sacral edema). Congestive heart failure can also cause edema in the lungs (pulmonary edema). This is not common, but the condition is life-threatening. It means the lungs are filling with fluid because the left side of the heart is not strong enough to pump the blood returning from the lungs. The blood gathers in the blood vessels of the lung, and fluid seeps out into the lung tissue. The signs are shortness of breath and rapid, shallow breathing or coughing.

Kidney disease could cause edema in the legs and around the eyes, because when the kidneys do not remove enough sodium and water from the body, the pressure in the blood vessels starts building up, which can lead to edema.

Low protein levels in the blood: If there is a lack of the protein albumin in the blood, fluid can leak out of blood vessels more easily. Low protein in the blood can be caused by extreme malnutrition, as well as kidney and liver diseases which mean that the body loses too much or produces too little protein.

Liver diseases: Scarring of liver tissue (liver cirrhosis) due to, for instance, long-term alcohol abuse or a liver inflammation, can cause edema in the abdomen (called ascites). This is because cirrhosis causes a lack of proteins and congestion in the liver, which can lead to increased pressure in the blood vessels. As a result, fluid seeps out into the abdomen.

Severe lung conditions like emphysema can also cause edema in the legs and feet if the pressure in the lungs and heart gets very high.

Oedema is the medical term for fluid retention in the body.

It occurs when there is a build-up of fluid (mainly water) in the body’s tissues, causing swelling to occur in the affected area.

As well as swelling or puffiness of the skin, oedema can cause:

  • skin discolouration
  • fluid-filled areas of skin that temporarily hold the imprint of your finger when pressed (known as pitting oedema)
  • aching, tender limbs
  • stiff joints
  • weight gain or weight loss
  • raised blood pressure and pulse rate

Oedema is often a symptom of an underlying condition. It can also be caused by a variety of factors such as high salt intake in the diet or being immobile for long periods of time (see below).

A common cause of fluid build-up in the tissues is a condition called lymphoedema. It occurs when the lymphatic system is damaged or disrupted.

The lymphatic system is a series of glands (lymph nodes) throughout the body. They are connected by a network of vessels, much like blood vessels. Fluid surrounding the body tissues normally drains from the tissues into the nearby lymph vessels to be transported away and emptied back into the blood.

If the lymphatic vessels are not working properly, for example because they are blocked, excess fluid cannot be reabsorbed and builds up in the tissues.

See the Health A-Z topic about Lymphoedema for information about its causes, symptoms, diagnosis, treatment and prevention.

Oedema can also be caused by the following conditions or treatments:

  • pregnancy
  • kidney disease
  • heart failure
  • chronic lung disease
  • thyroid disease
  • liver disease
  • diabetes
  • arthritis
  • malnutrition
  • medication, such as corticosteroids or medicine for high blood pressure
  • the contraceptive pill

If it occurs in the leg, the cause may be any of the following:

  • a blood clot
  • varicose veins
  • a growth or cyst

Oedema may also result from the following factors:

  • a high intake of salt in the diet
  • sitting or standing still for long periods of time
  • hot weather
  • exposure to high altitudes
  • burns to the skin

When doctors cannot find an obvious cause for oedema, it is know as idiopathic oedema.

Where it occurs

Oedema can occur in any tissue in the body, but it most commonly affects the hands, arms, feet, ankles and legs (this is known as peripheral oedema).

Other types of oedema include cerebral oedema (affecting the brain), pulmonary oedema (affecting the lungs) and macular oedema (affecting the eyes).


Oedema is usually cured by diagnosing and treating the underlying condition causing the imbalance of fluids in your body.

Your GP may recommend some simple self-care techniques to reduce the build-up of fluid in your body, such as reducing your salt intake, losing weight (if you are overweight) and raising your legs three to four times a day to improve your circulation.

Drugs called diuretics may be prescribed to reduce the build-up of fluid in your tissues. Diuretics increase the amount you urinate and are not suitable if you are pregnant or have weakened valves in the veins of your legs.

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