Zidoval Gel Side Effects: Complete Safety Guide
When Do Side Effects Start? How Long Do They Last? Timeline, Contraindications & Food Interactions
Key Takeaways: Zidoval Gel Side Effects
- Most common: Headache, nausea, metallic taste, vaginal irritation, and thrush (candidiasis).
- Onset: Side effects can start within hours of first use or appear after a few days.
- Duration: Most local effects resolve 2–3 days after stopping; systemic effects clear within 48 hours.
- Avoid alcohol: Drinking during treatment can cause severe nausea, flushing, and rapid heartbeat—avoid for 48 hours after last dose.
- Contraindications: Allergy to metronidazole or parabens, blood disorders, first trimester pregnancy (caution).
Zidoval gel is generally well tolerated, but like all medicines it can cause side effects. Understanding what to expect, when they might happen, and how long they last helps you use the gel safely. This guide explains everything based on the official patient information leaflet and clinical sources.
When to seek urgent medical help
If you experience signs of a severe allergic reaction (rash, itching, swelling of face/tongue, difficulty breathing), chest pain, confusion, or an erection lasting more than 4 hours (though unlikely with vaginal use), stop using the gel and seek immediate medical attention.
Common Side Effects of Zidoval Gel
Based on the patient information leaflet and clinical trials, side effects are divided by frequency. Most are mild and temporary.
Common (affect up to 1 in 10 people)
- Headache, dizziness
- Stomach cramps, nausea, vomiting
- Unpleasant or metallic taste in the mouth
- Dry skin, redness, itching, burning or stinging of the skin
- Vaginal thrush (candidiasis), vaginal discharge, pelvic discomfort
- Decreased appetite, depression
Uncommon (affect up to 1 in 100 people)
- Feeling sick, tiredness, irritability, difficulty sleeping
- Unusual sensations in fingers and toes (pins and needles)
- Diarrhoea, constipation, bloating, dry mouth
- Muscle cramps, darkened urine (harmless)
- Urinary tract infections, vulval swelling
- Changes in periods (spotting, painful periods)
Frequency not known
- Itchy rash (urticaria) – reported post-marketing
- Severe allergic reactions (very rare)
🗒️ Note: Darkened urine is harmless and caused by a metabolite of metronidazole. It does not mean you have a problem.
When Do Zidoval Gel Side Effects Start?
The timing varies depending on the type of side effect and individual sensitivity.
- Immediate (within hours): Local irritation, burning, or itching at the application site can occur shortly after inserting the gel. Some women may notice a temporary increase in discharge.
- Within 1–2 days: Headache, nausea, metallic taste, or dizziness may develop as the body absorbs a small amount of metronidazole.
- After a few doses (days 2–4): Vaginal thrush can appear because the antibiotic may disturb the natural balance of yeast. Also, any allergic skin reactions may take a couple of days to show.
- After finishing treatment: Some side effects like thrush might peak after the course ends, as the vaginal flora readjusts.
If you develop severe symptoms at any point, contact your doctor.
How Long Do Zidoval Gel Side Effects Last?
Most side effects are short-lived and resolve once the treatment stops or as your body adjusts.
| Side effect type | Typical duration |
|---|---|
| Local irritation (burning, itching) | Usually subsides within a few hours after each application; if persistent, may last up to 2–3 days after stopping the gel. |
| Headache, nausea, metallic taste | These systemic effects usually fade within 24–48 hours after the last dose as metronidazole is cleared from the body. |
| Vaginal thrush | May require antifungal treatment; without treatment, it can persist. With proper therapy, clears in a few days. |
| Allergic skin reactions | Mild rashes often resolve within a week of stopping; severe ones need medical attention. |
Because metronidazole has a half-life of 6–8 hours, it takes about 30–40 hours (roughly 1.5 days) for 95% of the absorbed drug to be eliminated. So systemic side effects like taste changes usually stop within 2 days of finishing the course.
Contraindications: Who Should NOT Use Zidoval Gel
Do not use Zidoval gel if any of the following apply:
- Allergy: You are allergic to metronidazole, other nitroimidazole antibiotics (e.g., tinidazole), or any of the ingredients (parabens, propylene glycol, etc.).
- Blood disorders: You have or have had blood problems (metronidazole can affect blood cell counts).
- Liver disease: Severe liver impairment requires caution; discuss with your doctor.
- First trimester of pregnancy: Generally avoided unless essential. In later pregnancy, only if clearly needed.
- Breastfeeding: Discuss with your doctor; metronidazole passes into breast milk. A temporary pause in breastfeeding may be advised.
- Children and elderly: Safety not established; not recommended for under 18s or the elderly.
Also avoid using during your period if possible, as blood can wash away the gel and reduce effectiveness.
Food Interactions: Alcohol and Other Considerations
The most important interaction is with alcohol.
- Alcohol: Drinking alcohol while using Zidoval gel can cause a disulfiram-like reaction: severe nausea, vomiting, flushing, headache, and rapid heartbeat. Avoid alcohol during the 5-day treatment and for at least 48 hours after your last dose.
- Food: No specific food interactions. The gel is applied vaginally, so eating does not affect absorption. However, a healthy diet may support recovery.
- Other medicines: Tell your doctor if you take blood thinners (warfarin), lithium, cyclosporin, or 5-fluorouracil—Zidoval may increase their effects.
Zidoval Gel Side Effects FAQs
Can Zidoval gel cause thrush?
Yes, vaginal thrush (candidiasis) is a common side effect because metronidazole kills bacteria, allowing yeast to overgrow. If you get itchy, thick discharge, ask your doctor for antifungal treatment.
Is it normal to have a metallic taste while using Zidoval?
Yes, a metallic or unpleasant taste is a known side effect. It happens because a small amount of metronidazole is absorbed into your bloodstream and reaches your saliva. It will disappear within a couple of days after finishing the course.
What should I do if I miss a dose?
Apply it as soon as you remember. If it's almost time for your next dose, skip the missed one—do not double up. Resume your usual schedule.
Can I drink alcohol 24 hours after my last dose?
No, you must wait at least 48 hours. Metronidazole stays in your system for about two days, and drinking earlier could still trigger a severe reaction.
Does Zidoval gel affect contraception?
Zidoval gel does not affect hormonal contraception (pill, patch, implant). However, the gel can weaken latex condoms and diaphragms, so use additional barrier protection (e.g., non-latex condoms) during treatment and for 3 days after.
Need Treatment for Bacterial Vaginosis?
If you have BV symptoms and want to discuss whether Zidoval gel is right for you, start an online consultation with a UK-registered doctor.
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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: 25 February 2026
Next Review: 25 August 2026
Published on: 25 February 2026
Last Updated: 25 February 2026