How To Get Rid Of Mold In Shower Caulk (6 Ways To Do It!)

Benjamin Wright
by Benjamin Wright

Mold can be one of the most troubling things that you will find in your home. The spores travel everywhere, and mold can actually be quite dangerous if left unchecked. You can find spores from mold all over your house; however, mold spores really love to flourish in warm, moist areas, like your bathroom.

Once mold has a steady diet and is multiplying unchecked, the problem spreads fast. The spores not only attach to your grout and caulk, but they will eventually get behind it and grow there as well.

There are several ways to get rid of mold in shower caulk. Scrubbing down your shower with hydrogen peroxide or white vinegar can kill a high percentage of the mold. You can also use bleach, baking soda, or borax. Scrub down your shower with the product and let sit for an hour before rinsing.

Follow along with the tips below to find out how to eliminate mold that takes root inside the caulk in your shower.

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What Causes Mold to Grow on the Caulk in Your Shower?

Many things can cause mold to grow in your shower. Before you can solve the problem, it is always best to know the source.

What does mold eat?

Mold is an organism and needs certain conditions in order to grow and thrive. The spores in mold spread through the air. They are hearty and live in spite of extreme conditions. Mold will feed on any kind of organic material, but they choose cellulose over any other option. This means mold will grow on drywall, particleboard, wood, or paper, which all contain cellulose.

What conditions does mold need to grow?

Other conditions mold needs to spread quickly are low light, oxygen, heat, moisture, and high humidity. This is why it loves bathrooms and showers. Your shower caulk will often hold small amounts of soap and water. Your soap typically contains cellulose in some form, and so the mold has a meal and a home. Left unchecked, mold will start to grow.

Other common reasons mold will grow in a home include wet clothes, leaks, condensation build-up, using a humidifier, and generally not keeping up with maintenance. An elevated number of spores in the home increases the possibility of mold growth in the shower.

How Does Mold in Your Home Affect Your Health?

Mold is actually quite dangerous, especially when left to grow without abandon. Most materials now used to construct your bathroom are made without cellulose to give mold less of a chance to grow. But as we’ve noted above, mold is a survivor, and it will still find a way.

Mold typically causes stronger reactions in those with allergies or sensitivities, weakened immune systems, or asthma, as well as chronic lung conditions. However, larger populations of mold can cause a reaction in anyone.

Symptoms of mold poisoning can include mild problems like skin irritation and rashes, yeast infections, sneezing, and itchy eyes. It can also cause severe problems like difficulty in breathing.

As you can see, dealing with your mold problems is not just about aesthetics. There are many reasons to remove mold from your home.

What Types of Cleaners Get Rid of the Mold on the Caulk in Your Shower?

To solve the problem of mold growing in your shower, consider the assorted options. Some work better than others in certain situations, and there are also varying degrees of intensity.

Tools You Might Need

  • Sponge
  • Spray Bottle
  • Cotton Balls
  • Broom + Dustpan OR Vacuum/Hand Vacuum
  • Old Toothbrush OR Soft Cleaning Brush

Spray Ammonia

First thing’s first – safety! Ammonia is not safe to breathe, so be sure to ventilate your bathroom by opening a window and the door all the way. The restricted airflow of your bathroom makes it great for mold and not so great for you.

If you have a fan that you can use to get the air circulating, use that. It is also recommended to use a respirator that can absorb the fumes. These are available at hardware stores or you can order them online. Rather than using no mask or one that doesn’t clearly state that it will absorb ammonia, try the other methods listed below and skip this one.

How to Use Ammonia

Mix the ammonia and water with a ratio of 1:1 inside a container. Create a mixture in a well-ventilated area. Use a funnel to pour the mixture into a bottle with a sprayer. Spray an even layer onto the caulk in your shower. In corners or other areas where there is an abundance of growth, spray more.

The ammonia will need to sit for 10 minutes, so use this time to leave the room and get some fresh air.

Head back in after 10 minutes and, using a soft brush, scrub until you see the mold coming off. Using a small rag or cloth, wipe down the caulk until it’s dry so you can see clearly. If there is mold remaining, repeat the process.

Keep an eye on it over the next days and weeks. If the mold returns, it has gotten under the caulk.


If you choose not to use ammonia, bleach is a decent alternative. Ammonia is stronger, however. Therefore, if you tried ammonia first, you won’t want to waste time trying this method. Do NOT mix ammonia with bleach. It creates a chlorine gas, and you will have much bigger problems than mold.

Again, begin by making sure the door to the bathroom is wide open, and any windows in the bathroom are open as well. Mix 1 part water with 1 part bleach. Then, follow one of the following methods for application.

Sponge – wet with the solution and apply it to the caulk. This is better for small spots.

Spray Bottle – funnel the bleach mixture into the bottle. Spray on mold and let it sit for twenty minutes, then wipe away.

Cotton Balls – for stubborn mold, soak cotton balls in the bleach mixture, but don’t squeeze the solution out. Place them directly on the caulk, trying to poke them into any holes or crevices with a pin or other object. Let it sit overnight. The next day, remove the cotton balls and scrub with a soft brush or sponge.


Vinegar is great because it doesn’t only get rid of the mold, the spores are killed as well.

Regular vinegar is the best to use, and there isn’t a mold species it can’t kill. Using straight vinegar is fine, but if the smell is too strong, you can dilute it. Just know that the more you dilute it, the more of it you’ll need to apply to get the job done.

Simply funnel the vinegar, or diluted vinegar, into a spray bottle and spray on the mold. Let it sit on there for an hour, then scrub with a soft brush or sponge. Finally, rinse it all down with water.

Because of the ease of this method, the low cost, the safety, and the fact that it kills the mold, vinegar is the preferred way to treat mold inside your home.

Baking Soda

While baking soda won’t kill the spores like the vinegar will, it can draw the moisture out of the caulk. This will prevent the spores from growing and spreading.

You can either make a solution of water and baking soda or a paste.

With the solution, dilute about half a teaspoon of baking soda into water in a spray bottle. Make sure it dissolves by shaking the bottle vigorously. Spray the solution on the caulk, and scrub the affected area with a soft brush.

Once you’re finished, rinse it all with water. Spray the mixture onto the caulk a second time, but let it sit and dry. It will help prevent the mold from coming back.

Alternatively, make a thick paste by adding some water to about a cup of baking soda. Spread it onto the mold spots on the caulk, and then let it sit for 20 minutes. Scrub with a soft brush until the mold is gone.

Hydrogen Peroxide

Peroxide is a safe way to remove mold, and it works for small to medium colonies. Be sure to grab a 3% solution. Funnel it into a bottle with a sprayer, and spray directly onto the caulk, ensuring it is thoroughly soaked.

Allow it to rest for 10 minutes, and then scrub with a sponge or soft brush. When you’re all done scrubbing, dry the caulk. If this method works for you, consider keeping a bottle on hand to use if the mold flares up again.


Tried and true, Borax is another option to get the mold off your shower caulk. Mix 10 parts water to 1 part Borax and funnel the mixture into your spray bottle. Just like above, spray onto the affected areas. You can scrub it right away or let it soak for a few minutes.

Remove Mold From Your Shower Caulk

Gather the tools you need to clean the area and remove the mold. This might include a vacuum or broom, sponges or brushes, and your cleaning solution.

Vacuum or wipe any dust or dirt off the shower caulk first, to avoid mixing dirt or dust into your cleaning solution.

  • Create your cleaning solution of choice
  • Spray/Soak/Scrub according to the method you chose above
  • Finally, rinse the caulk and dry everything thoroughly

What To Do If Nothing Worked

If the mold still remains, or you notice that the caulk is really stained, or crumbling in places, you may want to think about replacing the caulk either yourself or by hiring a professional.

Replacing the Caulk Yourself

If you choose to replace the caulk yourself, you will need to purchase a caulking gun, and some caulk. Make sure that it’s waterproof and recommended for showers. Generally, latex caulk is easier for DIY, but silicone is durable.

Remove the Caulk

You will also want caulk remover gel. Apply the gel and let it sit for at least 20 minutes, so the caulk becomes soft. Use a knife to remove the softened caulk.

Prepare the Site

Using painters tape, line the tiles on either side of the joint so just the part you want to caulk is showing. Cut the end of the nozzle on the new caulk bottle and make sure that it is the same width you’d like the caulk line to be.

Apply the Caulk

Squeeze the trigger on the caulk gun slowly while you draw a line of caulk directly along the seam. If you need to remove any excess caulk, get your fingers wet and run them on the line of caulk. Before the caulk dries. After that, remove the tape slowly.

You should have a perfectly beaded line. Now, wait according to the directions on the tube for the caulk to dry and enjoy your newly sealed shower.

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Related Questions

How Can I Prevent Future Mold Growth?

A solution of half a teaspoon of baking soda dissolved in water in a spray will help keep mold at bay. Spray occasionally along your caulk and grout and allow to dry completely. You can also be sure to wipe your shower down periodically to keep it dry. Using your bathroom fan, and keeping the door open, are also important measures to combat future mold growth.

Does mold grow on top of or inside of caulk?

While it may appear that mold grows on top of mold, it actually roots down into the caulk quite far. That is why it is difficult to remove permanently. Even after scrubbing mold away from the surface, it usually doesn’t take long for the mold to grow back, thanks to the roots within the caulk.

Benjamin Wright
Benjamin Wright

Benjamin is a proud homeowner who loves to write about DIY projects and home improvement projects. Traveling, perfecting his home, and spending time with his family are just a few of the many things that keep him inspired.

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