by | Apr 24, 2024 | Nurse Article | 0 comments

Principle Involved in the Administration of Injections


1. The knowledge of the anatomy and physiology of the body is essential for the safe administration of the injection.

a. To avoid injury to the underlying tissues.


Numerous blood vessels and nerves are lying below the skin. Careful selection of the site can avoid injury to these areas.

The common sites for the injection are:

Intradermal injections are given at the inner aspect of the lower arm, upper aspect of the anterior chest, and upper aspect of the posterior chest.

Subcutaneous injections are given on outer aspect of the aspect of the upper arm, posterior chest wall just below the scapula, anterior abdominal wall (from below breasts to the iliac crests), and anterior and lateral aspect of the thigh.

Intra-muscular injections are given on deltoid muscles of the shoulder, gluteal muscles of buttocks (inner angle of the upper and outer quadrant) rectus femoris muscles of the anterior aspect of the thigh, and vastus lateralis muscle on the lateral aspect of the thigh.

To give the intravenous injections, any visible and palpable veins are used. The most convenient veins are the basilic and median cubitus veins in the antcubital space of the arm.

The injections are never given in the medial aspect of the limbs for fear of nerve injuries.

Choose long needles for obese clients and short needles for emaciated clients, especially when intramuscular injections are given.


B. To Minimize pain.


The nearer to the surface a needle is placed and the fluid is introduced more is the pain. Unless contraindicated, all the medications are given deep into the muscles to aid quick absorption because muscles are richly supplied with blood supply than the subcutaneous tissue.

Pain is caused by the pressure of the fluid introduced into the tissues. Therefore, very small quantities of fluids are to be introduced intradermally. Large quantities are given subcutaneously and still larger quantities are given intramuscularly. Very large quantities are given intravenously.

To minimize the pain of injection, areas poorly supplied with sensory nerves are chose, e.g., the outer aspect of the limbs are chosen instead of the medial or inner aspect of the limbs.

Needles that are sharp and without hooks will minimize the tissue injury and thereby reduce the pain.


C. To aid in absorption of the drug.


The deeper the penetration of the fluid, the faster is the rate of absorption. The intramuscular injections are absorbed faster than the subcutaneous and intradermal injections.

Applications of warmth and massage stimulate circulation and aids in the absorption of the drug.

Solutions having the same osmotic pressure as the blood (e.g. isotonic solutions) are absorbed more quickly than other fluids. Water soluble drugs are absorbed more quickly than the only preparations.

2.  If carelessly given, injections are means of introducing infection into the body.


The syringes and needles should be properly sterilized.

The drugs should be sterile.

The water used for the preparation of solutions should be freshly distilled and sterile to prevent pyrogenic infections.

The entry of bacteria growing on the skin is prevented by proper cleaning of the skin before the injections are given.

The nurse washes her hands before and after the procedure.

The equipment used for the injections are sterilized and handled under strict aseptic conditions.

3. Drugs that change the chemical composition of the blood will endanger the life of the client, if not used cautiously.


The average pH value of the blood is 7.4. Buffer salts such as sodium bicarbonate and disodium phosphate that are present in the blood helps to maintain the pH value of blood at a constant level. If the pH value rises above 7.8 or fails below 7, life is endangered. Therefore all fluids given into the blood stream should conform as closely as possible to the reaction of the normal blood.

When sodium and potassium salts are ordered they are to be administered very carefully because they change the pH value of blood. Its action will affect the functions of the vital organs. Frequent checking of the vital signs is indicated.

Solutions having same osmotic pressure (isotonic) as the blood are safely administered e.g., physiologic saline. Those producing less osmotic pressure (hypotonic solutions) can haemolyse the blood cells. Those producing more osmotic pressure (hypertonic solutions) can cause shrinking of the blood cells.

4. Any unfamiliar situation produces anxiety.


Explanations of the procedure in advance the nurse to win the confidence and the cooperation of the client. Clients who are experiencing the injections first time may be under great tension.


Fear and anxiety increases the pain, probably due to the increased tension in the muscles. Proper explanations and positioning of the client can help the client to relax.

The sight of the syringe and needle cause fear and anxiety in the client. Therefore, avoid the sight of the syringe and needle before giving infections.

Pain of the injection may be prevented or alleviated by distracting the attention of the client from the injection by conversations.

Provide privacy if needed.


5. Once a drug is injected it is irretrievable. Antidote may be available for particular medications but the best antidote is prevention.


Make sure that there is proper medication order from the physician. In doubt, consult the physician.

Observe the five rights of the administration of medicine.

Make sure that there is adequate light in the work room.

Be up to date about the knowledge of the medications administered.

Some of the complications can be avoided:

Allergic reaction can be prevented by a test dose e.g. penicillin, serum etc.

Pyrogenic reactions can be prevented by using proper aseptic technique.

Regulating the flow of fluid can prevent the circulatory overload.

Rotation of the site of injection prevents induration of tissues.

Accidental intravascular injections can be avoided by checking for the presence of blood in the syringe, before the drug is injected.

Measuring the drug accurately and administrating at the correct time will prevent the overdosage and the under dosage of the medication.

Expelling the air from the syringe before introducing the needle into the veins can prevent air embolism.

Proper selection of the site can prevent injury to the nerves and other complications.

6. Organization and planning results in the economy of time, material and comfort. 


The nurse should be confident of the procedure by acquiring manual and technical skills.

Be vigilant to avoid errors in the administration of medicines.

Prepare the client both physically and mentally.

Assemble the equipment needed and arrange them according to the convenience of working.

Have all the equipment in order. 


1. Give injections only on the doctor’s written orders.

2. Follow strict aseptic techniques – in the sterilization of equipment, in the preparation of medications, in the administration of injections.

3. Syringes and needles used for injections should be kept separate from those used for other purposes. For example, keep the aspiration syringes only for that purpose and should not be mixed with the syringes used for injections.

4. Always have the syringes and needles in good order. Syringes should be airtight and the needles should be sharp and patent.

5. Change the needle after withdrawing the drug from a rubber stopped container before giving injection to the client. When the needle passes through the rubber stopper, there is a chance for the needle to become blunt.

6. Observe the ‘five rights’ of the administration of medicines while giving injections to anyone.

7. Never use a drug whose expiry date is over.

8. Always have the client relaxed and placed in a comfortable position. If possible let the client take a lying down position. When giving injection at the shoulder, ask the client to flex the arms at the elbow to relax the muscles at the shoulder. When the injections are given at the buttocks, place the  client in a prone position or in a lateral position with the knee flexed.

9. Never allow the client to walk soon after the injection as he should be watched for any reaction.

10. Always give a test dose in  case of penicillin and all types of sera before the first dose is administered to rule out any allergic reaction. After the full dose is given, keep the client under observation for any delayed reaction.

11. Expel the air from the syringe before the injection.

12. Select the appropriate site for giving injections. The site depends upon the type of medication, quantity ordered, and the route of administration. Do not give any injection into the tissues that are tender, painful, hot, oedematous, diseased or where there is scar tissue. Avoid bony prominences. Check the area for any induration of the tissue.

13. Rotate the site especially for client getting insulin to prevent Lipodystrophy (wasting of subcutaneous tissue).

14. Use correct technique of injection. The needle inserted gently and quickly, the drug injected slowly and the needle withdrawn gently and quickly will be helpful to reduce the pain.

15. After inserting the needle, always withdraw the piston make sure that it is not in a blood vessel in case of intramuscular and subcutaneous injections. If there is presence of blood in the syringe, withdraw the needle and give the injection at another site.

16. Solutions for injections should be clear, sterile, nearly neutral in reaction, isotonic if possible, non-haemolytic and contain only substances that are soluble in water, when used for intravenous injections.

17. Massage the area at the site of the injection except in case of intradermal injections and intravenous injections.
18. Injections should be charted immediately after it is administered by the person who has administered and should sign it. 


Preliminary Assessment

1. Check the diagnosis and the age of the client.

2. Check the purpose of the injection.

3. Check the physician’s orders for the type of injection, the dosage, the time and the route of administration.

4. Check the client’s name, bed number and other identification.

5. Check the nurse’s record to find the time at which the last dose was given.

6. Check the symptoms of over dosage or allergic reactions etc.

7. Check the necessity for giving test dose.

8. Check the form of the medication available and the correct method of administration.

9. Check the consciousness of the client and the ability to follow directions.

10. Check the site of injection where the last dose was given and the site where the next dose is to be given. Check the areas for redness, pain, itching, induration, skin lesions, sloughing, and abscess formation. If anyone of the symptoms is present, report it to the charge nurse and rotate the site.

11. Check the client’s previous experiences with the injections.

12. Check the abilities and the limitations.