Can I go to the mosque with a cold or flu?

It's better to stay home while you're contagious. Islam excuses sick people from congregational prayer, including Jumu'ah, and asks us not to harm others. A mild sniffle is fine if you're careful, but with a fever, a heavy cough or the flu, pray at home and still get the full reward.

Illness is a valid excuse

Going to the mosque is a great deed, but it is never meant to make you sicker or spread a virus to others. The Prophet ﷺ listed the sick among those who do not have to attend Friday prayer (Sunan Abi Dawud 1067). Scholars of all four schools agree that real illness excuses you from praying in congregation, and from Jumu'ah too, where you pray the normal four-rak'ah Dhuhr at home instead.

لَا يُكَلِّفُ ٱللَّهُ نَفْسًا إِلَّا وُسْعَهَا "Allah does not charge a soul except [with that within] its capacity..." Quran 2:286

You still get the reward

If you normally go to the mosque and miss it because you're ill, you don't lose out. The Prophet ﷺ said that when a person falls ill or travels, he is credited with the same reward as the deeds he used to do when healthy and at home (Sahih al-Bukhari 2996). So resting is not laziness; it's part of how Allah made the religion easy.

Don't harm the people next to you

In the mosque you stand shoulder to shoulder, share prayer mats and greet people up close. That makes it easy to pass on a cold. The Prophet ﷺ told people who had eaten raw garlic or onion to keep away from the mosque so they wouldn't bother others (Sahih al-Bukhari 855). Scholars reason that something contagious is an even stronger reason to stay away. Elderly worshippers, pregnant women and people with weak immunity are at the mosque too. See Can I eat garlic before going to the mosque?

If it's only a mild cold

Stand at the edge of a row or near the back, and keep greetings to a smile and salam.
Bring your own prayer mat and tissues, and wash your hands before and after.
Wear a mask if it makes others feel safer; it doesn't affect your prayer.
Skip shaking hands and hugging. Nobody will mind once you say you have a cold.
Make dua for recovery. See What dua can I say when I'm sick?

Missing Jumu'ah while sick

Missing Friday prayer for a real illness is not a sin, even if it happens a few weeks in a row. Pray Dhuhr at home on time, and many people also listen to their mosque's khutbah online for the reminder. See Can I pray Jumu'ah at home? For serious or long illnesses, follow your doctor's advice about when you're no longer contagious.

Key points

Real illness excuses you from congregation and Jumu'ah.
You keep the reward of the prayers you usually attend.
With flu, fever or a heavy cough, pray at home.
With a mild cold, keep your distance and be considerate.

Tip: Keep a small "sick day" routine: pray on time at home, read a page of Quran, and message a friend from the mosque. It keeps you connected until you're back in the rows.