What to do when you get sick in your first 90 days

Getting sick in your first 90 days feels higher-stakes than it is. You’re new. You don’t yet know what the norms are. You worry that taking a day will register as “first-year who can’t hack it.” So you half-work through the fever, send a couple of replies that don’t quite make sense, and everyone comes away mildly worried about you.

Don’t do that. Sick days are normal. Managers expect them. The only thing that goes wrong in your first 90 days is not the sick day — it’s the way some new hires handle it.

Here’s the short version of how to handle it well.

The morning-of message

Send it early. Before the day starts, not two hours into the morning. Keep it short. Give your manager the three things they need, nothing more.

Hey [Manager] —
Woke up with a bad cold / stomach bug / etc. Going to take today
to rest. I'll check messages briefly mid-morning to flag anything
urgent, but I'll be offline otherwise. If anyone needs X today,
Sarah has the context.
Back tomorrow (or will update you in the morning if I'm not).

Four things in that message:

1. What’s wrong, one phrase. Cold, stomach thing, migraine, injury. “Not feeling well” is vague enough to sound fishy. “Cold” is honest and specific enough that nobody wonders.
2. The plan. “Taking today to rest” is a plan. “I might try to work a little” is not a plan and worries your manager.
3. Coverage. If there’s a concrete thing that needed you today, name the backup. Shows judgment.
4. When to expect you back. Default to “back tomorrow.” If you’re clearly going to need more, say so now, don’t stretch one-day-at-a-time.

That’s it. Send it and then stop managing the office.

The thing to absolutely not do

Don’t try to work sick from home unless you are in a role where absolutely being on is mandatory and you can actually function. The output you produce with a fever is unreliable. The emails you send are worse than the emails you’d send not sick. The Slack messages you type half-conscious are the ones coworkers remember awkwardly for a year.

Your manager would much rather you take a real day off than send low-quality output pretending everything is fine. “I worked through it” is not the badge you think it is in your first year. “I took the day, came back clear-headed Wednesday, and shipped the thing” is a better story.

How many days is normal?

In most US corporate jobs, a cold or a flu takes one to three days. A stomach bug is usually one day. Covid can be a week. These are not alarming. Nobody counts.

What gets noticed is the shape:

• One honest day, with a clear message, comes back clear-headed: normal, nothing to explain.
• Two or three days for something clearly communicated: normal.
• A week+ without clear communication or a check-in: concerning. If you’re going to be out more than three days, tell your manager on day two, not day five.
• Frequent single-day absences without a pattern: can look avoidant. If this is you and you’re chronically unwell, it’s worth a conversation with your manager about it explicitly — not every time, but once, framed as “I’ve had a few rough weeks with allergies / migraines / etc., didn’t want you wondering.”

Don’t try to hide a recurring issue by camouflaging it as individual one-off days. Managers notice the pattern eventually and it’s worse when they’ve noticed without you naming it.

What to do while you’re out

Rest.

If you’re really bored: nothing. Watch TV. Sleep. Do not answer Slacks, do not “just quickly send this email,” do not check in halfway through the day to prove you’re virtuous. The day off is the product. Shipping it well means actually taking it.

One exception: if something blows up that genuinely only you can unblock — a client escalation, a deploy gone wrong — triage it briefly, hand it to someone, and return to rest. Don’t try to fully handle it.

The return-to-work message

The day you come back, low-key:

Hey [Manager] — back today. Caught up on the most urgent threads.
Picking up X and Y first; Z slid to later this week — I'll shift
the timeline in the doc. Let me know if priorities moved while I
was out.

Three lines. You’re oriented, you’re picking up the work, and you’ve proactively flagged the one thing that slipped. That last piece is the move most people skip. Acknowledging the slip upfront saves your manager from having to ask.

Do not apologize profusely. “I’m so sorry for being out, I really feel terrible about it” makes your manager feel weird. You were sick. You took a sick day. You’re back. A short, oriented message is all they want.

What if you’re sick during a high-stakes week

Three possibilities, in order:

1. Handoff with time. If you know Monday is going to be bad and Wednesday is the client meeting, message your manager Monday morning with the handoff plan, not a hope that you’ll recover in time. Better to over-handle the handoff than under-handle it and fumble the meeting Wednesday.
2. Ask for help. If you’re too sick to plan a clean handoff, say that explicitly: “Too rough today to plan the handoff cleanly — if you could have Sarah cover the Tuesday review, I can catch up Wednesday.” Managers respect this because it’s specific and solvable.
3. Show up sick, and tell everyone you’re sick. If the meeting is a Q1 board call and you actually have to be there, you can show up, but name it at the top of the meeting: “Wanted to flag — I’m on the tail end of a cold, so apologies in advance if I’m a little off. Let’s get to the substance.” Sets expectations.

What your manager is actually thinking

Most managers react to sick days from new hires in one of three ways:

• “Thanks for the heads-up, feel better.” That’s 85% of the time.
• “Is everything okay?” — when they’re being genuinely kind. Not a trap.
• “Huh, that’s two sick days in three weeks.” — when there’s a pattern. If you see this, it’s time for the “by the way, here’s what’s going on” conversation.

Very few managers secretly judge first-year sick days harshly. The ones who do are the same managers who will find something else to judge harshly, and there is no game you can play with them that makes it better.

Edge cases

• Mental-health days. Most companies say the right words about these but in practice a vague “feeling off today” is fine. You don’t owe anyone the specifics.
• Kids sick, not you. “My kid woke up sick — I’ll be handling it most of today, may be on Slack intermittently but not reliable.” Same rules, different subject.
• Long-term illness. If you’re dealing with something that’s going to require more than a few days over a couple of months, HR is the right conversation, not your manager. US workplaces have specific protections here and you want the formal process on your side.

Do this today

Save a draft of the morning-of message in your notes app. Not because you’re planning to be sick, but because when you wake up at 7 AM with a bad cold, you don’t want to be composing the message through a fog. Fill it in, send it, sleep till noon. This is the version you’ll be glad you have.

For the first-week rhythm that builds enough credit that a day off doesn’t feel costly, see the week 1 checklist. For the broader first-90-days system, see the First 90 Days OS.