Bubble Under Skin After Ozempic Injection: Causes and Prevention

A bubble under the skin after an Ozempic injection is a common occurrence that typically results from the medication temporarily pooling in the subcutaneous tissue before absorption. Ozempic (semaglutide) is administered as a subcutaneous injection, and the visible swelling usually resolves within hours as the solution disperses through the fatty tissue. Whilst most injection site bubbles are harmless and require no treatment, understanding proper injection technique, site rotation, and warning signs of complications can help patients manage this GLP-1 receptor agonist therapy safely and effectively. This article explains why bubbles form, when to seek medical advice, and how to prevent injection site reactions.

What Causes a Bubble Under the Skin After Ozempic Injection?

A bubble or raised area under the skin following an Ozempic (semaglutide) injection typically results from the medication being deposited into the subcutaneous tissue layer. This is the intended injection site, but the visible swelling occurs when the liquid medication temporarily accumulates in one area before being absorbed into the bloodstream. Ozempic is formulated as a clear, colourless solution that requires time to disperse through the fatty tissue beneath the skin.

Several factors contribute to bubble formation at injection sites. Injection technique plays a crucial role—if the needle is not inserted at the appropriate angle or to sufficient depth, the medication may pool closer to the skin surface. The injection speed also matters; administering the dose too quickly can create localised pressure and visible swelling. Additionally, individual tissue characteristics vary between patients, with some people having less subcutaneous fat in certain areas, making bubbles more noticeable.

Lipohypertrophy represents another potential cause, particularly in patients who repeatedly inject into the same site. This condition involves the abnormal accumulation of fatty tissue at frequently used injection sites, creating lumps that can persist for weeks or months. When medication is injected into these areas, absorption may be impaired, and visible swelling becomes more pronounced. Regular site rotation is essential to prevent this complication.

It is important to distinguish between a temporary bubble caused by normal medication deposition and other injection site reactions such as localised inflammation, infection, or allergic response. Most bubbles resolve within hours as the medication disperses, whereas persistent lumps, increasing pain, redness, or warmth may indicate complications requiring medical assessment. If you experience difficulty breathing or facial/throat swelling, seek emergency medical attention by calling 999 or attending A&E immediately.

According to the Ozempic Summary of Product Characteristics, approved injection sites include the abdomen, thigh, or upper arm.

Is a Lump or Bubble After Ozempic Injection Normal?

In most cases, a small bubble or temporary lump following Ozempic injection is considered a normal physiological response and does not indicate a problem with the medication or injection technique. The subcutaneous tissue naturally requires time to absorb the semaglutide solution, and a visible raised area may persist for several minutes to a few hours post-injection. This is particularly common when patients first begin treatment and are still developing their injection technique.

However, certain characteristics warrant closer attention. A bubble that resolves within 24 hours without associated symptoms is typically benign. Patients should monitor for signs that might suggest complications, including:

• Persistent lumps lasting beyond 24-48 hours

• Increasing size, hardness, or tenderness at the injection site

• Redness, warmth, or signs of inflammation suggesting possible infection

• Bruising or bleeding that seems excessive

• Itching, rash, or hives indicating potential allergic reaction

According to the UK Summary of Product Characteristics for Ozempic, injection site reactions are classified as 'uncommon' (may affect up to 1 in 100 people). These reactions are generally mild and transient.

When to seek medical advice:

• Lumps that do not resolve within 24-48 hours

• Signs of infection (increasing pain, pus, fever)

• Severe bruising or bleeding

• For urgent concerns when your GP is unavailable, contact NHS 111

When to seek emergency help (call 999 or go to A&E):

• Difficulty breathing

• Facial or throat swelling

• Other symptoms of severe allergic reaction

Most injection site bubbles require no specific treatment beyond observation and improved injection technique for future doses. Suspected side effects can be reported via the MHRA Yellow Card scheme (yellowcard.mhra.gov.uk).

How to Prevent Injection Site Reactions with Ozempic

Preventing injection site reactions, including bubble formation, requires a systematic approach to injection preparation and site management. Rotation of injection sites represents the single most important preventive measure. Ozempic should be injected subcutaneously in the abdomen, thigh, or upper arm, with patients advised to use a different injection site each week. Within each anatomical area, injections should be spaced at least 2–3 centimetres apart to allow tissue recovery and prevent lipohypertrophy, as recommended by the Forum for Injection Technique UK (FIT UK).

The abdomen (excluding a 5 cm radius around the navel) offers the most consistent absorption and largest surface area for rotation. The anterior and lateral thigh provides an alternative site with good subcutaneous tissue depth, whilst the upper arm (posterior aspect) may be used but often requires assistance from another person for self-injection. Keeping a written or digital log of injection sites helps ensure proper rotation and prevents inadvertent reuse of the same location.

Temperature management of the medication also influences injection comfort and tissue reaction. According to the UK SmPC, Ozempic should be stored in the refrigerator (2–8°C) until first use, then may be kept at room temperature (below 30°C) or in a refrigerator for up to 6 weeks (42 days). Keep the pen cap on when not in use to protect from light and do not freeze. Allowing the pen to reach room temperature before injection can improve comfort.

Skin preparation should follow these steps:

• Wash hands thoroughly with soap and water

• Clean the injection site with an alcohol wipe and allow to dry completely (30–60 seconds)

• Avoid injecting through clothing or into areas with skin conditions, scars, or moles

• Do not massage or rub the injection site before or immediately after injection

Additional preventive measures include using appropriate needle length (FIT UK recommends 4 mm pen needles for most adults) and avoiding injection into areas with reduced blood flow or excessive scarring. Never share your Ozempic pen with others, even if the needle is changed, and always dispose of used needles safely in an approved sharps container.

Proper Ozempic Injection Technique to Avoid Skin Bubbles

Mastering correct injection technique significantly reduces the likelihood of bubble formation and ensures optimal medication absorption. The Ozempic pen is designed for ease of use, but attention to specific technical details makes a substantial difference in patient experience and treatment efficacy.

Step-by-step injection technique:

1. Preparation phase

• Remove the pen cap and attach a new needle for each injection (never reuse needles)

• For a new pen only: perform the flow check as instructed in the patient information leaflet to ensure proper pen function

• Select and dial the prescribed dose (0.25 mg for initiation, then 0.5 mg, 1 mg, or 2 mg as directed)

2. Skin preparation and positioning

• For 4 mm needles (recommended by FIT UK for most adults), a skin pinch is generally not required when injecting at 90 degrees

• If using longer needles or if you have very little subcutaneous fat, gently pinch a fold of skin between thumb and forefinger

• This technique helps ensure the needle reaches subcutaneous fat rather than muscle

3. Needle insertion

• Insert the needle at a 90-degree angle to the skin surface in one smooth, swift motion

• The entire needle should penetrate the skin—hesitation or partial insertion increases bubble risk

• For very thin patients or when using longer needles, a 45-degree angle may be more appropriate

4. Medication delivery

• Press and hold the dose button firmly until the dose counter shows "0"

• Keep the needle in the skin and continue holding the button for at least 6 seconds after the counter shows "0" (count slowly: "one-thousand-one, one-thousand-two...")

• This crucial step allows complete medication delivery and prevents backflow

5. Withdrawal and post-injection care

• Release the skin pinch (if used) before withdrawing the needle

• Remove the needle straight out at the same angle as insertion

• Do not rub or massage the injection site—this can cause medication to leak back out

• Apply gentle pressure with a clean tissue if minor bleeding occurs

• Safely dispose of the used needle in an approved sharps container

Common technical errors that cause bubbles:

• Insufficient wait time after the counter shows "0" (most common error)

• Withdrawing the needle whilst still pressing the dose button

• Injecting into areas with insufficient subcutaneous fat

• Reusing needles, which become blunted and cause more tissue trauma

• Not holding the pen steady during the full injection process

If a bubble consistently appears despite correct technique, consider adjusting the injection site to an area with more subcutaneous tissue or consult your diabetes specialist nurse for personalised guidance. Some patients benefit from having their technique observed by a healthcare professional to identify subtle errors. The NHS provides injection technique training through diabetes clinics, and many areas offer refresher sessions to ensure ongoing best practice.

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