How Long Does Metronidazole Take to Work?

Metronidazole is an antibiotic commonly used to treat bacterial vaginosis, an infection that causes an imbalance in naturally occurring bacteria in the vagina.

Metronidazole for bacterial vaginosis will begin to work straight away because it is quickly absorbed. It reaches its maximum concentration between one and two hours after you have taken it. Most people notice an improvement in their symptoms within a few days.

Here, we’ll explore how quickly metronidazole works against bacterial vaginosis, why you should finish the course, and give you some self-care tips if you currently have bacterial vaginosis.

How quickly does metronidazole work?

When you take metronidazole tablets (or use metronidazole gel), they start working almost immediately. Because it is so well absorbed by the body, metronidazole reaches its peak concentration in the blood within two hours.

Most people who take metronidazole to treat bacterial vaginosis will feel better within a few days, but it may take a week or longer for some.

How does metronidazole work?

Metronidazole works by killing the bacteria causing the infection through:

• Diffusing into the bacteria
• Interacting with bacterial DNA to stop more DNA from being made
• Loss of DNA structure causes cell death in the bacteria

Figure 1. Bacterial vaginosis (BV) occurs when the relative abundance of bacterial vaginosis bacteria increases and outnumbers healthy Lactobacilli species. The presence of BV bacteria increases vaginal inflammation and releases inflammatory cytokines. When metronidazole is administered BV bacteria numbers reduce, Lactobacilli abundance increases, and inflammation lowers. Together this helps to increase the integrity of the epithelial barrier and removes the infection. (Source: Armstrong et al., (2022))

Why is it important to complete your course of metronidazole?

It is important to finish the course of metronidazole that your clinician has prescribed, even if you are feeling better. That’s because the infection could come back if you stop your treatment early.

If you finish treatment early, then a small number of bacteria may remain in the body. Without antibiotics, these bacteria numbers can grow and cause the infection to come back.

What is bacterial vaginosis?

Bacterial vaginosis is a common infection caused by an imbalance in healthy and pathogenic bacteria in the vagina.

The prevalence of bacterial vaginosis is shown in the graph below:

Graph 1. According to figures from the National Institute for Health and Care Excellence (NICE), the reported prevalence of BV in the UK is 5% in asymptomatic college students, 12% in pregnant women who attend ante-natal classes, 30% in women who are terminating a pregnancy, 45-55% in black women, and 5-15% in Caucasian women.

Bacterial vaginosis symptoms

The symptoms of bacterial vaginosis include:

• an unusual vaginal discharge that has a strong fishy smell
• greyish-white discharge
• watery, thin discharge

Around 50% of women do not get any symptoms.

How to relieve bacterial vaginosis symptoms at home

If you have bacterial vaginosis, there are things you can do at home to help ease your symptoms and stop it from coming back.

They are:

• wash your genital area with water and plain soap
• have showers instead of baths
• avoid using perfumed soap, shower gel, shampoo, or bubble bath
• do not use vaginal deodorants, washes, or douches
• use sensitive fabric detergents and conditioners to wash your underwear
• avoid smoking

Find out more about how you can prevent bacterial vaginosis by reading our short guide: Do’s and don’ts: Preventing BV.

What to do if you think you have bacterial vaginosis

If you think you have bacterial vaginosis, you should seek medical advice from a clinician. Bacterial vaginosis is not usually serious, but you’ll need antibiotics to clear the infection.

If you keep getting recurrent bacterial vaginosis, find out why by reading our ‘Why do I keep getting bacterial vaginosis?’ guide.

Where can I buy antibiotics for bacterial vaginosis?

The usual treatment for bacterial vaginosis is metronidazole. You can buy Metronidazole online from Prescription Doctor with a private prescription.

To request metronidazole from one of our clinicians, you will need to:

• Fill out a short online medical questionnaire. The answers you provide will let our clinicians assess if metronidazole is an appropriate bacterial vaginosis treatment for you.
• If approved, your order will be delivered the next day. If your order is approved by 3 pm on a weekday, our UK-registered pharmacy will dispatch your medication the same day via a next-day service.
• If your order isn’t approved, you’ll receive a full refund. If our clinician doesn’t think metronidazole is suitable for you, you will receive a full refund as part of Prescription Doctor’s money-back guarantee.

Alternative bacterial vaginosis treatments

If metronidazole tablets aren’t right for you, then at Prescription Doctor we can offer Zidoval as an alternative. It is a vaginal gel which contains metronidazole as its active ingredient. Rather than taking a tablet, Zidoval is a gel which is inserted into your vagina and used once daily for five days.

Authored By

Leanne Edermaniger

Medical Content Writer

Leanne is a science and health content writer focusing on human health and biology while utilising her solid academic background.

Published on: 11/08/2023

Reviewed By

Mohamed Imran Lakhi

MPharm - Lead Pharmacist

Imran Lakhi is the superintendent pharmacist and founder at Prescription Doctor. He has been at the core of our team.

Reviewed on: 28/06/2024