Stud 100 Spray Side Effects: Complete Safety Guide
When Do Side Effects Start? How Long Do They Last? Timeline, Contraindications & Food Interactions
Key Takeaways: Stud 100 Side Effects
- Most common: Local irritation, redness, rash – usually mild and short-lived.
- Onset: Local effects can appear within minutes; allergic reactions may take longer.
- Duration: Mild side effects fade within hours; systemic effects (rare) last until drug clears (~12h).
- Contraindications: Allergy to lidocaine, broken skin, liver/kidney disease (seek advice).
- Food interaction: None direct; avoid excessive alcohol to prevent dizziness.
- Emergency: Stop use and seek help if severe swelling, convulsions, or breathing difficulty occurs.
Stud 100 Spray contains lidocaine, a local anaesthetic. While generally safe when used as directed, some men may experience side effects. This guide explains what they are, when they start, how long they last, and who should avoid using it – based on the official Patient Information Leaflet (PIL) and UK clinical sources.
Important Medical Advice
If you or your partner develop a rash, swelling, or difficulty breathing after using Stud 100, stop use immediately and seek medical help. In rare cases, high blood levels of lidocaine can cause nervousness, dizziness, convulsions, or loss of consciousness – this requires urgent attention.
What Are Stud 100 Spray Side Effects?
The PIL lists the following possible side effects:
- Common (may affect up to 1 in 10): Mild irritation, redness, or rash at the application site.
- Uncommon/rare: Allergic reactions (skin rash, itching, swelling). Very rare: severe allergic reactions.
- Systemic effects (extremely rare with correct use): If too much is absorbed (e.g., overuse or broken skin), lidocaine can cause nervousness, dizziness, blurred vision, convulsions, or slowed heart rate. This requires about 25 times the recommended dose, according to the PIL.
Partner side effects: If the spray is not washed off before intercourse, your partner may experience temporary vaginal numbness or irritation.
When Do Stud 100 Spray Side Effects Start?
The onset of side effects depends on the type:
- Local irritation: Can occur within minutes of application – a burning or stinging sensation that usually fades quickly.
- Allergic contact dermatitis: May appear hours after use, as it involves an immune reaction.
- Systemic toxicity (very rare): Would typically occur 30–60 minutes after application if a large amount enters the bloodstream.
If you experience any side effect, note the time and stop using the product.
How Long Do Stud 100 Side Effects Last?
- Mild local irritation: Usually resolves within 30 minutes to a few hours as the lidocaine wears off.
- Allergic rash: May last 1–3 days after stopping use; antihistamines or steroid cream may help – consult a pharmacist.
- Systemic effects: If they occur, they last until lidocaine is cleared from the body – half-life ~2 hours, so effects may persist for 4–12 hours depending on severity.
Partner numbness, if it occurs, typically resolves within 1–2 hours as the lidocaine is absorbed or washed away.
Stud 100 Side Effects Timeline
| Time after application | Possible side effects |
|---|---|
| 0–15 minutes | Burning, stinging, redness at application site (common but temporary). |
| 15 minutes – 2 hours | Allergic reaction (rash, itching) may begin; partner numbness if transferred. |
| 2–12 hours | Local irritation subsides; allergic rash may persist. Systemic effects (if any) peak and then decline. |
| 12–24 hours | Most effects fully resolved. If rash persists beyond 24 hours, consult a doctor. |
Contraindications: Who Should NOT Use Stud 100
According to the PIL, do not use Stud 100 if:
- You or your partner are allergic to lidocaine or any other ingredient (see section 6 of PIL).
- You have broken, irritated, or inflamed skin on the penis.
- You have severe liver or kidney disease – seek medical advice before use.
- You are taking certain antiarrhythmic medicines (e.g., mexiletine) – check with your doctor.
- You are under 18 years of age.
Also, if you have a history of seizures or heart block, consult a doctor before using any lidocaine product.
Food Interactions & Other Considerations
Food: Stud 100 is a topical spray, so food does not interact. You can eat normally before or after use.
Alcohol: The PIL does not list a direct interaction, but excessive alcohol can increase the risk of dizziness or impairment. If you feel dizzy after using Stud 100, avoid alcohol until you know how the spray affects you.
Other medicines: Although systemic absorption is minimal, tell your doctor if you are taking antiarrhythmics or strong CYP3A4 inhibitors (e.g., ketoconazole) as they could theoretically increase lidocaine levels.
Driving: Stud 100 is unlikely to impair driving, but if you experience dizziness, do not drive.
Stud 100 Safety FAQs
What are the most common side effects of Stud 100?
Local skin irritation, redness, or rash at the application site are the most common. These usually resolve quickly.
How soon after applying Stud 100 can side effects start?
Local reactions like burning or itching can appear within minutes. Allergic reactions may take a few minutes to hours.
How long do Stud 100 side effects last?
Mild local irritation usually fades within a few hours. If systemic effects occur (very rare), they may last until the drug is cleared (about 12 hours).
Can I drink alcohol while using Stud 100?
Moderate alcohol is unlikely to cause issues, but excessive alcohol may increase dizziness or impairment. Avoid binge drinking.
Who should not use Stud 100?
Anyone allergic to lidocaine or any ingredients, or with broken/inflamed skin. Consult a doctor if you have liver or kidney problems.
Concerned About Side Effects? Speak to a Doctor
If you're unsure whether Stud 100 is safe for you, or if you've experienced side effects and need advice, a confidential online consultation with a UK-registered doctor can help.
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Medical Content Manager
Nabeel is a co-founder, and medical content manager of Chemist Doctor. He works closely with our medical team to ensure the information is accurate and up-to-date.
Medical Doctor
Dr. Feroz is a GMC-registered doctor and a medical reviewer at Chemist Doctor. He oversees acute condition and urgent care guidance.
Medical Director
Usman is a co-founder, and medical director of Chemist Doctor. He leads the organisation's strategic vision, bridging clinical and operational priorities.
Review Date: 26 February 2026
Next Review: 26 August 2026
Published on: 26 February 2026
Last Updated: 26 February 2026